Patent Publication Number: US-2023165161-A1

Title: Magnetic memory devices

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This U.S. non-provisional patent application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2021-0164209, filed on Nov. 25, 2021, in the Korean Intellectual Property Office, and the entire contents of the above-identified application are hereby incorporated by reference. 
     BACKGROUND 
     The present disclosure relates to magnetic memory devices, and more particularly, to magnetic memory devices that use movement phenomena of magnetic domain walls. 
     High-speed and low-voltage memory devices have been increasingly demanded to realize high-speed and low-power electronic devices that include such memory devices. Magnetic memory devices have been studied as memory devices that potentially satisfy these demands. In particular, magnetic memory devices have been spotlighted as potential next-generation memory devices because of their high-speed operation characteristics and/or non-volatile characteristics. In particular, new magnetic memory devices using movement phenomena of magnetic domain walls of magnetic materials have been studied and developed. 
     SUMMARY 
     Some embodiments of the inventive concepts of the present disclosure may provide a magnetic memory device capable of controlling more stably a position of a magnetic domain wall in a magnetic track including a synthetic antiferromagnetic structure. 
     Some embodiments of the inventive concepts of the present disclosure may also provide a magnetic memory device capable of reducing a current density for moving a magnetic domain wall in a magnetic track including a synthetic antiferromagnetic structure. 
     In some embodiments, a magnetic memory device may include a magnetic track that extends in a first direction. The magnetic track may include a lower magnetic layer that extends in the first direction, an upper magnetic layer that extends in the first direction on the lower magnetic layer, a spacer layer that extends in the first direction between the lower magnetic layer and the upper magnetic layer, and a non-magnetic pattern that penetrates the upper magnetic layer and is on the spacer layer. The non-magnetic pattern may have a first junction surface that is in contact with a first portion of the upper magnetic layer, and a second junction surface that is in contact with a second portion of the upper magnetic layer. The lower magnetic layer and the upper magnetic layer may be antiferromagnetically coupled to each other by the spacer layer. 
     In some embodiments, a magnetic memory device may include a conductive line that extends in a first direction, and a magnetic track that extends in the first direction on the conductive line. The magnetic track may include a lower magnetic layer, a spacer layer and an upper magnetic layer, which are sequentially stacked on the conductive line in a second direction perpendicular to the first direction, and a non-magnetic pattern that penetrates the upper magnetic layer and is on the spacer layer. The non-magnetic pattern may have a first junction surface that is in contact with a first portion of the upper magnetic layer, and a second junction surface that is in contact with a second portion of the upper magnetic layer. The non-magnetic pattern may vertically overlap with a portion of the lower magnetic layer in the second direction, and the lower magnetic layer and the upper magnetic layer may be antiferromagnetically coupled to each other by the spacer layer. 
     In some embodiments, a magnetic memory device may include a conductive line that extends in a first direction; and a lower magnetic layer, a spacer layer, and an upper magnetic layer that are sequentially stacked on the conductive line in a second direction perpendicular to the first direction, the lower magnetic layer and the upper magnetic layer antiferromagnetically coupled to each other by the spacer layer; and a non-magnetic pattern that is within the upper magnetic layer and on the spacer layer, the non-magnetic pattern comprising a first junction surface that is in contact with a first portion of the upper magnetic layer; and a second junction surface that is in contact with a second portion of the upper magnetic layer. The non-magnetic pattern may vertically overlap with a lower magnetic domain wall in the lower magnetic layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view schematically illustrating a magnetic memory device according to some embodiments of the inventive concepts. 
         FIG.  2    is a cross-sectional view illustrating a magnetic memory device according to some embodiments of the inventive concepts 
         FIG.  3    is an enlarged view of a portion ‘A’ of  FIG.  2   . 
         FIGS.  4 A and  4 B  are enlarged views corresponding to the portion ‘A’ of  FIG.  2    to illustrate movement of a magnetic domain wall by applying a current in a magnetic track of a magnetic memory device according to some embodiments of the inventive concepts. 
         FIGS.  5 A and  5 B  are enlarged views corresponding to the portion ‘A’ of  FIG.  2    to illustrate movement of a magnetic domain wall by an external magnetic field in a magnetic track of a magnetic memory device according to some embodiments of the inventive concepts. 
         FIG.  6    is a plan view illustrating a portion of a magnetic memory device according to some embodiments of the inventive concepts. 
         FIGS.  7 A to  7 C  are cross-sectional views corresponding to the portion ‘A’ of  FIG.  2    to illustrate a method of manufacturing a magnetic memory device according to some embodiments of the inventive concepts. 
         FIG.  8    is a plan view illustrating a method of manufacturing a magnetic memory device according to some embodiments of the inventive concepts. 
         FIG.  9    is a cross-sectional view illustrating a magnetic memory device according to some embodiments of the inventive concepts. 
         FIG.  10    is a cross-sectional view illustrating a magnetic memory device according to some embodiments of the inventive concepts. 
     
    
    
     DETAILED DESCRIPTION 
     Some examples of embodiments of the inventive concepts will now be described more fully with reference to the accompanying drawings. 
       FIG.  1    is a perspective view schematically illustrating a magnetic memory device according to some embodiments of the inventive concepts. 
     Referring to  FIG.  1   , a magnetic memory device may include a conductive line CL, a magnetic track MTR on the conductive line CL, and a read/write unit  150  on the magnetic track MTR. Each of the conductive line CL and the magnetic track MTR may extend in a first direction D 1  and may have a line shape in which a length in the first direction D 1  is greater than a width in a second direction D 2  perpendicular to the first direction D 1 . The first direction D 1  and the second direction D 2  may be parallel to a plane (e.g., a plane that includes a bottom surface CL_L of the conductive line CL) and may be perpendicular to each other. The magnetic track MTR may be stacked on the conductive line CL in a third direction D 3  that is perpendicular to the first direction D 1  and the second direction D 2 . The third direction D 3  may be perpendicular to the plane discussed above (e.g., the plane that includes the bottom surface CL_L of the conductive line CL). The read/write unit  150  may be adjacent to a portion of the magnetic track MTR. 
     The conductive line CL may be configured to generate spin-orbit torque by a current flowing therethrough. The conductive line CL may include a material capable of generating a spin hall effect or a Rashba effect by a current flowing in the first direction D 1  or an opposite direction to the first direction D 1  in the conductive line CL. The conductive line CL may include a heavy metal having an atomic number of 30 or more and may include, as examples, iridium (Ir), ruthenium (Ru), tantalum (Ta), platinum (Pt), palladium (Pd), bismuth (Bi), titanium (Ti), or tungsten (W). 
     The magnetic track MTR may include a lower magnetic layer  110 , a spacer layer  120  and an upper magnetic layer  130 , which are sequentially stacked on the conductive line CL in the third direction D 3 . The lower magnetic layer  110  may be between the conductive line CL and the spacer layer  120 , and the spacer layer  120  may be between the lower magnetic layer  110  and the upper magnetic layer  130 . Each of the lower magnetic layer  110 , the spacer layer  120  and the upper magnetic layer  130  may have a line shape extending in the first direction D 1 . 
     The conductive line CL and the magnetic track MTR may have straight line shapes extending in the first direction D 1 , but embodiments of the inventive concepts are not limited thereto. In some embodiments, the conductive line CL and the magnetic track MTR may have U-shaped line shapes. 
     The lower magnetic layer  110  may include lower magnetic domains D_L arranged in the first direction D 1 , and lower magnetic domain walls DW_L between the lower magnetic domains D_L. Each of the lower magnetic domains D_L may be a region in the lower magnetic layer  110  in which magnetic moments are aligned in a certain direction, and each of the lower magnetic domain walls DW_L may be a region in which directions of magnetic moments are changed between the lower magnetic domains D_L. The lower magnetic domains D_L and the lower magnetic domain walls DW_L may be alternately arranged in the first direction D 1 . 
     The upper magnetic layer  130  may include upper magnetic domains D_U arranged in the first direction D 1 , and upper magnetic domain walls DW_U between the upper magnetic domains D_U. Each of the upper magnetic domains D_U may be a region in the upper magnetic layer  130  in which magnetic moments are aligned in a certain direction, and each of the upper magnetic domain walls DW_U may be a region in which directions of magnetic moments are changed between the upper magnetic domains D_U. The upper magnetic domains D_U and the upper magnetic domain walls DW_U may be alternately arranged in the first direction D 1 . The upper magnetic domains D_U may vertically overlap with the lower magnetic domains D_L, respectively, in the third direction D 3 . 
     The lower magnetic layer  110  and the upper magnetic layer  130  may be antiferromagnetically coupled to each other by the spacer layer  120 . A magnetic moment of the upper magnetic layer  130  may be greater than a magnetic moment of the lower magnetic layer  110 . Each of the lower magnetic layer  110  and the upper magnetic layer  130  may include a magnetic element and may include at least one of, as examples, cobalt (Co), iron (Fe), or nickel (Ni). The spacer layer  120  may include a non-magnetic metal and may include, as examples, ruthenium (Ru), iridium (Ir), tungsten (W), tantalum (Ta), or any alloy thereof. 
     The magnetic track MTR may further include at least one non-magnetic pattern  140  in the upper magnetic layer  130 . The non-magnetic pattern  140  may penetrate the upper magnetic layer  130  and may be on the spacer layer  120 . The non-magnetic pattern  140  may be in contact with a top surface of the spacer layer  120 . The non-magnetic pattern  140  may be between a pair of upper magnetic domains DU, adjacent to each other in the first direction D 1 , of the upper magnetic domains D_U in the upper magnetic layer  130 . The non-magnetic pattern  140  may vertically overlap (e.g., in the third direction D 3 ) with a portion of the lower magnetic layer  110  in the third direction D 3 . For example, the non-magnetic pattern  140  may vertically overlap with a corresponding lower magnetic domain wall DW_L of the lower magnetic domain walls DW_L in the lower magnetic layer  110 . The spacer layer  120  may be between the lower magnetic layer  110  and the upper magnetic layer  130  and may extend between the non-magnetic pattern  140  and the lower magnetic layer  110 . The non-magnetic pattern  140  may include a metal oxide. The non-magnetic pattern  140  may include a same magnetic element as a magnetic element in the upper magnetic layer  130  and may further include oxygen. 
     The at least one non-magnetic pattern  140  may be a plurality of non-magnetic patterns  140 . The plurality of non-magnetic patterns  140  may be spaced apart from each other in the first direction D 1  in the upper magnetic layer  130 . Each of the plurality of non-magnetic patterns  140  may penetrate the upper magnetic layer  130  and may be on the spacer layer  120 . Each of the plurality of non-magnetic patterns  140  may be in contact with the top surface of the spacer layer  120 . Each of the plurality of non-magnetic patterns  140  may be between a pair of upper magnetic domains D_U, adjacent to each other in the first direction D 1 , of the upper magnetic domains D_U in the upper magnetic layer  130 . Each of the plurality of non-magnetic patterns  140  may vertically overlap (e.g., in the third direction D 3 ) with a corresponding portion of the lower magnetic layer  110  in the third direction D 3  and, for example, may vertically overlap with a corresponding lower magnetic domain wall DW_L of the lower magnetic domain walls DW_L in the lower magnetic layer  110 . The spacer layer  120  may be between the lower magnetic layer  110  and the upper magnetic layer  130  and may extend between the plurality of non-magnetic patterns  140  and the lower magnetic layer  110 . 
     The non-magnetic pattern  140  may have a first surface  140 S 1  and a second surface  140 S 2 , which are opposite to each other in the first direction D 1 . The first surface  140 S 1  of the non-magnetic pattern  140  may be in contact with a portion of the upper magnetic layer  130  (e.g., a first portion of the upper magnetic layer  130 ), and the second surface  140 S 2  of the non-magnetic pattern  140  may be in contact with another portion of the upper magnetic layer  130  (e.g., a second portion of the upper magnetic layer  130 ). The first surface  140 S 1  of the non-magnetic pattern  140  may be referred to as a first junction surface  140 S 1  between the non-magnetic pattern  140  and the upper magnetic layer  130 , and the second surface  140 S 2  of the non-magnetic pattern  140  may be referred to as a second junction surface  140 S 2  between the non-magnetic pattern  140  and the upper magnetic layer  130 . 
     The magnetic track MTR may include synthetic antiferromagnetic regions SAF adjacent to each other in the first direction D 1 , and a ferromagnetic region FM between the synthetic antiferromagnetic regions SAF. The synthetic antiferromagnetic regions SAF may be regions in which the lower magnetic layer  110  and the upper magnetic layer  130  are antiferromagnetically coupled to each other by the spacer layer  120 . The ferromagnetic region FM may include the non-magnetic pattern  140 , and the portion of the lower magnetic layer  110  which vertically overlaps with the non-magnetic pattern  140 . The magnetic track MTR may include a synthetic antiferromagnet-ferromagnet-synthetic antiferromagnet (SAF-FM-SAF) bi-lateral junction structure in which the synthetic antiferromagnetic regions SAF and the ferromagnetic region FM therebetween are joined to each other in the first direction D 1 . The first junction surface  140 S 1  between the non-magnetic pattern  140  and the upper magnetic layer  130  may be referred to as a first junction surface  140 S 1  between one of the synthetic antiferromagnetic regions SAF and the ferromagnetic region FM, and the second junction surface  140 S 2  between the non-magnetic pattern  140  and the upper magnetic layer  130  may be referred to as a second junction surface  140 S 2  between the other of the synthetic antiferromagnetic regions SAF and the ferromagnetic region FM. In some embodiments, the magnetic track MTR may have a structure in which a plurality of synthetic antiferromagnetic regions SAF and a plurality of ferromagnetic regions FM are alternately arranged in the first direction D 1 . 
     The read/write unit  150  may be on at least one synthetic antiferromagnetic region SAF of the synthetic antiferromagnetic regions SAF of the magnetic track MTR. The read/write unit  150  may include a GMR sensor using a giant magneto resistance effect or a TMR sensor using a tunnel magneto resistance effect. For example, the read/write unit  150  may include a magnetic pattern  154  on the upper magnetic layer  130 , a tunnel barrier pattern  152  between the upper magnetic layer  130  and the magnetic pattern  154 , and an electrode pattern  156  on the magnetic pattern  154 . The magnetic pattern  154  may be between the tunnel barrier pattern  152  and the electrode pattern  156 . The magnetic pattern  154  may include at least one of cobalt (Co), iron (Fe), or nickel (Ni). The tunnel barrier pattern  152  may include at least one of magnesium (Mg) oxide, titanium (Ti) oxide, aluminum (Al) oxide, magnesium-zinc (Mg—Zn) oxide, or magnesium-boron (Mg—B) oxide. The electrode pattern  156  may include a conductive material and may include, for example, a metal (e.g., copper, tungsten, or aluminum) and/or a metal nitride (e.g., tantalum nitride, titanium nitride, or tungsten nitride). 
     The read/write unit  150  may vertically overlap (e.g., in the third direction D 3 ) with a corresponding upper magnetic domain D_U of the upper magnetic domains D_U in the upper magnetic layer  130  and a corresponding lower magnetic domain D_L of the lower magnetic domains D_L in the lower magnetic layer  110 . 
       FIG.  2    is a cross-sectional view illustrating a magnetic memory device according to some embodiments of the inventive concepts, and  FIG.  3    is an enlarged view of a portion ‘A’ of  FIG.  2   . Hereinafter, the descriptions to the same features as mentioned with reference to  FIG.  1    will be omitted for the purpose of ease and convenience in explanation. 
     Referring to  FIGS.  2  and  3   , the lower magnetic domains D_L in the lower magnetic layer  110  and the upper magnetic domains D_U in the upper magnetic layer  130  may have perpendicular magnetic anisotropy (PMA). Each of the lower magnetic domains D_L in the lower magnetic layer  110  may have a magnetization direction  110 M substantially perpendicular to an interface between the lower magnetic layer  110  and the spacer layer  120 , and the magnetization directions  110 M of lower magnetic domains D_L adjacent directly to each other may be opposite to each other. Each of the lower magnetic domain walls DW_L may define a boundary between the adjacent lower magnetic domains D_L having the magnetization directions  110 M opposite to each other. Each of the upper magnetic domains D_U in the upper magnetic layer  130  may have a magnetization direction  130 M substantially perpendicular to an interface between the upper magnetic layer  130  and the spacer layer  120 , and the magnetization directions  130 M of upper magnetic domains D_U adjacent directly to each other may be opposite to each other. Each of the upper magnetic domain walls DW_U may define a boundary between the adjacent upper magnetic domains D_U having the magnetization directions  130 M opposite to each other. 
     The upper magnetic domains D_U may vertically overlap with the lower magnetic domains D_L in the third direction D 3 , respectively, and the upper magnetic domains D_U and the lower magnetic domains D_L may be antiferromagnetically coupled to each other by the spacer layer  120 . The magnetization direction  130 M of each of the upper magnetic domains D_U may be antiparallel to the magnetization direction  110 M of a corresponding lower magnetic domain D_L of the lower magnetic domains D_L. In the synthetic antiferromagnetic regions SAF of the magnetic track MTR, the upper magnetic domains D_U and the lower magnetic domains D_L may be antiferromagnetically coupled to each other by the spacer layer  120 . 
     The non-magnetic pattern  140  may vertically overlap with a portion of the lower magnetic layer  110  in the third direction D 3 . The non-magnetic pattern  140  and the portion of the lower magnetic layer  110  may constitute the ferromagnetic region FM of the magnetic track MTR. At least one lower magnetic domain wall DW_L of the lower magnetic domain walls DW_L may be in the portion of the lower magnetic layer  110  and may vertically overlap with the non-magnetic pattern  140  in the third direction D 3 . 
     The non-magnetic pattern  140  may have a width  140 W in the first direction D 1 . The width  140 W of the non-magnetic pattern  140  may be equal to or greater than a width of each of the lower magnetic domain walls DW_L in the first direction D 1 . In some embodiments, the width  140 W of the non-magnetic pattern  140  may be substantially equal to the width of each of the lower magnetic domain walls DW_L in the first direction D 1 . In this case, one lower magnetic domain wall DW_L of the lower magnetic domain walls DW_L may be in the portion of the lower magnetic layer  110  and may vertically overlap with the non-magnetic pattern  140  in the third direction D 3 . For example, the width  140 W of the non-magnetic pattern  140  may range from about 10 nm to about 20 nm. 
     When a plurality of non-magnetic patterns  140  is provided, each of the plurality of non-magnetic patterns  140  may vertically overlap with a corresponding portion of the lower magnetic layer  110 . Each of the plurality of non-magnetic patterns  140  and the corresponding portion of the lower magnetic layer  110  may constitute the ferromagnetic region FM of the magnetic track MTR. At least one lower magnetic domain wall DW_L of the lower magnetic domain walls DW_L may be in the corresponding portion of the lower magnetic layer  110  and may vertically overlap with a corresponding one of the plurality of non-magnetic patterns  140  in the third direction D 3 . The width  140 W of each of the plurality of non-magnetic patterns  140  may be equal to or greater than the width of each of the lower magnetic domain walls DW_L in the first direction D 1 . In some embodiments, the width  140 W of each of the plurality of non-magnetic patterns  140  may be substantially equal to the width of each of the lower magnetic domain walls DW_L in the first direction D 1 . In this case, one lower magnetic domain wall DW_L of the lower magnetic domain walls DW_L may be in the corresponding portion of the lower magnetic layer  110  and may vertically overlap with the corresponding one of the plurality of non-magnetic patterns  140  in the third direction D 3 . 
     When a current flows in the first direction D 1  or the opposite direction to the first direction D 1  in the conductive line CL, the lower magnetic domain walls DW_L in the lower magnetic layer  110  may move in the first direction D 1 . The movement of the lower magnetic domain walls DW_L may be due to spin-orbit torque and Dzyaloshinskii-Moriya interaction (DMI) generated at an interface between the conductive line CL and the lower magnetic layer  110 . A movement direction of the lower magnetic domain walls DW_L may be dependent on chirality of the lower magnetic domain walls DW_L. Since the lower magnetic domain walls DW_L in the lower magnetic layer  110  move in the first direction D 1 , the upper magnetic domain walls DW_U in the upper magnetic layer  130  may also move in the first direction D 1 . The movement of the upper magnetic domain walls DW_U may be due to the antiferromagnetic coupling between the lower magnetic layer  110  and the upper magnetic layer  130 . 
     The magnetic pattern  154  of the read/write unit  150  may have perpendicular magnetic anisotropy (PMA). The magnetic pattern  154  may have a magnetization direction  154 M that is substantially perpendicular to an interface between the magnetic pattern  154  and the tunnel barrier pattern  152 , and the magnetization direction  154 M of the magnetic pattern  154  may be fixed in one direction. The magnetization directions  130 M of the upper magnetic domains D_U in the upper magnetic layer  130  and the magnetization directions  110 M of the lower magnetic domains D_L in the lower magnetic layer  110  may be changeable to be parallel or antiparallel to the magnetization direction  154 M of the magnetic pattern  154 . 
     The magnetic pattern  154  may vertically overlap (e.g., in the third direction D 3 ) with a corresponding upper magnetic domain D_U of the upper magnetic domains D_U and a corresponding lower magnetic domain D_L of the lower magnetic domains D_L. The magnetic pattern  154 , the corresponding upper magnetic domain D_U and the corresponding lower magnetic domain D_L, which vertically overlap with each other, may constitute a magnetic tunnel junction MTJ. The magnetic pattern  154  may be a pinned layer having the magnetization direction  154 M fixed in one direction, and the corresponding upper magnetic domain D_U and the corresponding lower magnetic domain D_L may be antiferromagnetically coupled to each other to constitute a free layer having a synthetic antiferromagnetic structure. 
     In a read operation, a read current Iread may flow through the magnetic tunnel junction MTJ. A resistance state of the magnetic tunnel junction MTJ may be detected by the read current Iread. Whether the magnetic tunnel junction MTJ is in a high-resistance state or a low-resistance state may be detected by the read current Iread. Data ( 0  or  1 ) stored in the free layer may be detected from the resistance state of the magnetic tunnel junction MTJ. In a write operation, a write current Isw may flow through the magnetic tunnel junction MTJ. A magnitude of the write current Isw may be greater than a magnitude of the read current Iread. The magnetization direction  130 M of the corresponding upper magnetic domain D_U may be switched by spin transfer torque generated by the write current Isw. The magnetization direction  130 M of the corresponding upper magnetic domain D_U may be switched to be parallel or antiparallel to the magnetization direction  154 M of the magnetic pattern  154 , by the spin transfer torque generated by the write current Isw. The magnetization direction  1  OM of the corresponding lower magnetic domain D_L may be switched to be antiparallel to the magnetization direction  130 M of the corresponding upper magnetic domain D_U, by the antiferromagnetic coupling between the corresponding upper magnetic domain D_U and the corresponding lower magnetic domain D_L. 
     In some embodiments, each of the lower magnetic layer  110 , the upper magnetic layer  130  and the magnetic pattern  154  may include at least one of cobalt (Co), iron (Fe), or nickel (Ni) and may further include at least one non-magnetic material such as boron (B), zinc (Zn), aluminum (Al), titanium (Ti), ruthenium (Ru), tantalum (Ta), silicon (Si), silver (Ag), gold (Au), copper (Cu), carbon (C), and/or nitrogen (N). For example, each of the lower magnetic layer  110 , the upper magnetic layer  130  and the magnetic pattern  154  may include at least one of a perpendicular magnetic material (e.g., CoFeTb, CoFeGd, or CoFeDy), a perpendicular magnetic material having a L 1   0  structure, a CoPt alloy having a hexagonal close packed (HCP) lattice structure, or a perpendicular magnetic structure. The perpendicular magnetic material having the L 1   0  structure may include at least one of FePt having the L 1   0  structure, FePd having the L 1   0  structure, CoPd having the L 1   0  structure, or CoPt having the L 1   0  structure. The perpendicular magnetic structure may include magnetic layers and non-magnetic layers, which are alternately and repeatedly stacked. For example, the perpendicular magnetic structure may include at least one of (Co/Pt)n, (CoFe/Pt)n, (CoFe/Pd)n, (Co/Pd)n, (Co/Ni)n, (CoNi/Pt)n, (CoCr/Pt)n, or (CoCr/Pd)n, where ‘n’ denotes the number of bilayers. In some embodiments, each of the lower magnetic layer  110 , the upper magnetic layer  130  and the magnetic pattern  154  may include CoFeB or a Co-based Heusler alloy. 
     Referring to  FIG.  3   , the magnetic track MTR may include the synthetic antiferromagnetic regions SAF adjacent to each other in the first direction D 1 , and the ferromagnetic region FM between the synthetic antiferromagnetic regions SAF. One of the synthetic antiferromagnetic regions SAF may be referred to as a first synthetic antiferromagnetic region SAF 1 , and the other of the synthetic antiferromagnetic regions SAF may be referred to as a second synthetic antiferromagnetic region SAF 2 . The ferromagnetic region FM may be between the first synthetic antiferromagnetic region SAF 1  and the second synthetic antiferromagnetic region SAF 2 . The first junction surface  140 S 1  between the non-magnetic pattern  140  and the upper magnetic layer  130  may be referred to as a first junction surface  140 S 1  between the first synthetic antiferromagnetic region SAF 1  and the ferromagnetic region FM, and the second junction surface  140 S 2  between the non-magnetic pattern  140  and the upper magnetic layer  130  may be referred to as a second junction surface  140 S 2  between the second synthetic antiferromagnetic region SAF 2  and the ferromagnetic region FM. 
     At least one lower magnetic domain wall DW_L of the lower magnetic domain walls DW_L in the lower magnetic layer  110  may be in the ferromagnetic region FM and may vertically overlap with the non-magnetic pattern  140 . Lower magnetic domains D_L, adjacent to each other in the first direction D 1 , of the lower magnetic domains D_L in the lower magnetic layer  110  may be in the synthetic antiferromagnetic regions SAF, respectively. The adjacent lower magnetic domains D_L may include a first lower magnetic domain D_L 1  in the first synthetic antiferromagnetic region SAF 1 , and a second lower magnetic domain D_L 2  in the second synthetic antiferromagnetic region SAF 2 . The first lower magnetic domain D_L 1  and the second lower magnetic domain D_L 2  may be directly adjacent to each other in the first direction D 1  with the at least one lower magnetic domain wall DW_L interposed therebetween. Magnetization directions  110 M of the first lower magnetic domain D_L 1  and the second lower magnetic domain D_L 2  may be opposite to each other. For example, the magnetization direction  110 M of the first lower magnetic domain D_L 1  may be an up direction, and the magnetization direction  110 M of the second lower magnetic domain D_L 2  may be a down direction. 
     Upper magnetic domains D_U that are adjacent to each other in the first direction D 1  in the upper magnetic layer  130  may be in the synthetic antiferromagnetic regions SAF. The adjacent upper magnetic domains D_U may include a first upper magnetic domain D_U 1  in the first synthetic antiferromagnetic region SAF 1 , and a second upper magnetic domain D_U 2  in the second synthetic antiferromagnetic region SAF 2 . The first upper magnetic domain D_U 1  and the second upper magnetic domain D_U 2  may be adjacent directly to each other in the first direction D 1  with the non-magnetic pattern  140  interposed therebetween. The first upper magnetic domain D_U 1  and the second upper magnetic domain D_U 2  may vertically overlap with the first lower magnetic domain D_L 1  and the second lower magnetic domain D_L 2  (e.g., in the third direction D 3 ), respectively. Magnetization directions  130 M of the first upper magnetic domain D_U 1  and the second upper magnetic domain D_U 2  may be opposite to each other. For example, the magnetization direction  130 M of the first upper magnetic domain D_U 1  may be a down direction, and the magnetization direction  130 M of the second upper magnetic domain D_U 2  may be an up direction. In the synthetic antiferromagnetic regions SAF, the first upper magnetic domain D_U 1  and the second upper magnetic domain D_U 2  may be antiferromagnetically coupled to the first lower magnetic domain D_L 1  and the second lower magnetic domain D_L 2  by the spacer layer  120 , respectively. 
       FIGS.  4 A and  4 B  are enlarged views corresponding to the portion ‘A’ of  FIG.  2    to illustrate movement of a magnetic domain wall by applying a current in a magnetic track of a magnetic memory device according to some embodiments of the inventive concepts. 
     Referring to  FIGS.  3  and  4 A , when a current I flows in the conductive line CL in the first direction D 1 , the at least one lower magnetic domain wall DW_L in the ferromagnetic region FM may move into the second synthetic antiferromagnetic region SAF 2  in the first direction D 1 . Since the at least one lower magnetic domain wall DW_L moves, a magnetization direction  110 M of the lower magnetic layer  110  in the ferromagnetic region FM may be aligned in the up direction, and the magnetization direction  110 M of the second lower magnetic domain D_L 2  in the second synthetic antiferromagnetic region SAF 2  may be reversed to the up direction. In addition, the magnetization direction  130 M of the second upper magnetic domain D_U 2  in the second synthetic antiferromagnetic region SAF 2  may be reversed to the down direction by the antiferromagnetic coupling between the lower magnetic layer  110  and the upper magnetic layer  130 . Since the magnetization direction  130 M of the second upper magnetic domain D_U 2  is reversed, an upper magnetic domain wall DW_U may be formed in the upper magnetic layer  130  in the second synthetic antiferromagnetic region SAF 2 . The upper magnetic domain wall DW_U may move along with the at least one lower magnetic domain wall DW_L in the first direction D 1  by the antiferromagnetic coupling between the lower magnetic layer  110  and the upper magnetic layer  130 . 
     Referring to  FIGS.  3  and  4 B , when the current I flows in the conductive line CL in the opposite direction to the first direction D 1 , the at least one lower magnetic domain wall DW_L in the ferromagnetic region FM may move into the first synthetic antiferromagnetic region SAF 1  in the opposite direction to the first direction D 1 . Since the at least one lower magnetic domain wall DW_L moves, a magnetization direction  110 M of the lower magnetic layer  110  in the ferromagnetic region FM may be aligned in the down direction, and the magnetization direction  110 M of the first lower magnetic domain D_L 1  in the first synthetic antiferromagnetic region SAF 1  may be reversed to the down direction. In addition, the magnetization direction  130 M of the first upper magnetic domain D_U 1  in the first synthetic antiferromagnetic region SAF 1  may be reversed to the up direction by the antiferromagnetic coupling between the lower magnetic layer  110  and the upper magnetic layer  130 . Since the magnetization direction  130 M of the first upper magnetic domain D_U 1  is reversed, an upper magnetic domain wall DW_U may be formed in the upper magnetic layer  130  in the first synthetic antiferromagnetic region SAF 1 . The upper magnetic domain wall DW_U may move along with the at least one lower magnetic domain wall DW_L in the opposite direction to the first direction D 1  by the antiferromagnetic coupling between the lower magnetic layer  110  and the upper magnetic layer  130 . 
       FIGS.  5 A and  5 B  are enlarged views corresponding to the portion ‘A’ of  FIG.  2    to illustrate movement of a magnetic domain wall by an external magnetic field in a magnetic track of a magnetic memory device according to some embodiments of the inventive concepts. 
     Referring to  FIGS.  3  and  5 A , when a direction of an external magnetic field H applied to the magnetic track MTR is the down direction, the at least one lower magnetic domain wall DW_L in the ferromagnetic region FM may move in the opposite direction to the first direction D 1 . The at least one lower magnetic domain wall DW_L may be far away from the second junction surface  140 S 2  between the second synthetic antiferromagnetic region SAF 2  and the ferromagnetic region FM and may be close to the first junction surface  140 S 1  between the first synthetic antiferromagnetic region SAF 1  and the ferromagnetic region FM. 
     The at least one lower magnetic domain wall DW_L may not be injected into the first synthetic antiferromagnetic region SAF 1 . For example, a coercivity (Hc) of the synthetic antiferromagnetic regions SAF may be greater than a coercivity (Hc) of the ferromagnetic region FM. Since the synthetic antiferromagnetic regions SAF have the relatively great coercivity (Hc), the magnetization directions  110 M and  130 M of the lower magnetic layer  110  (e.g., the first and second lower magnetic domains D_L 1  and D_L 2 ) and the upper magnetic layer  130  (e.g., the first and second upper magnetic domains D_U 1  and D_U 2 ) in the synthetic antiferromagnetic regions SAF may not be reversed by the external magnetic field H. In addition, a magnetic moment of the upper magnetic layer  130  may be greater than a magnetic moment of the lower magnetic layer  110 . Since the direction of the external magnetic field H is the same direction (e.g., the down direction) as the magnetization direction  130 M of the first upper magnetic domain D_U 1  in the first synthetic antiferromagnetic region SAF 1 , the antiferromagnetic coupling between the first upper magnetic domain D_U 1  and the first lower magnetic domain D_L 1  in the first synthetic antiferromagnetic region SAF 1  may be stable with respect to the external magnetic field H. Thus, the at least one lower magnetic domain wall DW_L in the ferromagnetic region FM may not be injected into the first synthetic antiferromagnetic region SAF 1  but may be trapped in the lower magnetic layer  110  in the ferromagnetic region FM. 
     Referring to  FIGS.  3  and  5 B , when the direction of the external magnetic field H applied to the magnetic track MTR is the up direction, the at least one lower magnetic domain wall DW_L in the ferromagnetic region FM may move in the first direction D 1 . The at least one lower magnetic domain wall DW_L may be far away from the first junction surface  140 S 1  between the first synthetic antiferromagnetic region SAF 1  and the ferromagnetic region FM and may be close to the second junction surface  140 S 2  between the second synthetic antiferromagnetic region SAF 2  and the ferromagnetic region FM. 
     The at least one lower magnetic domain wall DW_L may not be injected into the second synthetic antiferromagnetic region SAF 2 . For example, since the synthetic antiferromagnetic regions SAF have the relatively great coercivity (Hc), the magnetization directions  110 M and  130 M of the lower magnetic layer  110  (e.g., the first and second lower magnetic domains D_L 1  and D_L 2 ) and the upper magnetic layer  130  (e.g., the first and second upper magnetic domains D_U 1  and D_U 2 ) in the synthetic antiferromagnetic regions SAF may not be reversed by the external magnetic field H. In addition, the magnetic moment of the upper magnetic layer  130  may be greater than the magnetic moment of the lower magnetic layer  110 . Since the direction of the external magnetic field H is the same direction (e.g., the up direction) as the magnetization direction  130 M of the second upper magnetic domain D_U 2  in the second synthetic antiferromagnetic region SAF 2 , the antiferromagnetic coupling between the second upper magnetic domain D_U 2  and the second lower magnetic domain D_L 2  in the second synthetic antiferromagnetic region SAF 2  may be stable with respect to the external magnetic field H. Thus, the at least one lower magnetic domain wall DW_L in the ferromagnetic region FM may not be injected into the second synthetic antiferromagnetic region SAF 2  but may be trapped in the lower magnetic layer  110  in the ferromagnetic region FM. 
     As described with reference to  FIGS.  3 ,  4 A and  4 B , the at least one lower magnetic domain wall DW_L in the ferromagnetic region FM may move into the synthetic antiferromagnetic regions SAF by the current I applied to the conductive line CL. However, as described with reference to  FIGS.  3 ,  5 A and  5 B , the at least one lower magnetic domain wall DW_L in the ferromagnetic region FM may not move into the synthetic antiferromagnetic regions SAF but may be trapped in the ferromagnetic region FM, when the external magnetic field H is applied to the magnetic track MTR. 
     According to the inventive concepts, the magnetic track MTR may include the synthetic antiferromagnet-ferromagnet-synthetic antiferromagnet (SAF-FM-SAF) bi-lateral junction structure in which the synthetic antiferromagnetic regions SAF and the ferromagnetic region FM therebetween are joined to each other in the first direction D 1 . The ferromagnetic region FM may include the non-magnetic pattern  140  and a portion of the lower magnetic layer  110  which vertically overlaps with the non-magnetic pattern  140 , and at least one lower magnetic domain wall DW_L may be in the portion of the lower magnetic layer  110  (i.e., in the ferromagnetic region FM). In this case, the at least one lower magnetic domain wall DW_L in the ferromagnetic region FM may move into the synthetic antiferromagnetic regions SAF by the current I applied to the conductive line CL but may not move into the synthetic antiferromagnetic regions SAF by the external magnetic field H applied to the magnetic track MTR. In other words, when the external magnetic field H is applied to the magnetic track MTR, the at least one lower magnetic domain wall DW_L in the ferromagnetic region FM may be trapped in the ferromagnetic region FM. Thus, it may be possible to minimize the influence of an external factor (e.g., the external magnetic field H) on positions of the lower magnetic domain walls DW_L in the lower magnetic layer  110 , and the positions of the lower magnetic domain walls DW_L in the lower magnetic layer  110  may be controlled more stably by the current I applied to the conductive line CL. In addition, since the positions of the lower magnetic domain walls DW_L in the lower magnetic layer  110  may be controlled more stably, positions of the upper magnetic domain walls DW_U in the upper magnetic layer  130  may also be controlled more stably due to the antiferromagnetic coupling between the lower magnetic layer  110  and the upper magnetic layer  130 . 
     As a result, the embodiments of the inventive concepts may provide the magnetic memory device capable of stably controlling a position of the magnetic domain wall in the magnetic track MTR including the synthetic antiferromagnetic structure. 
       FIG.  6    is a plan view of  FIG.  3    to illustrate a portion of a magnetic memory device according to some embodiments of the inventive concepts. 
     Referring to  FIGS.  3  and  6   , the first junction surface  140 S 1  between the non-magnetic pattern  140  and the upper magnetic layer  130  may be referred to as a first junction surface  140 S 1  between the first synthetic antiferromagnetic region SAF 1  and the ferromagnetic region FM, and the second junction surface  140 S 2  between the non-magnetic pattern  140  and the upper magnetic layer  130  may be referred to as a second junction surface  140 S 2  between the second synthetic antiferromagnetic region SAF 2  and the ferromagnetic region FM. 
     The first junction surface  140 S 1  between the first synthetic antiferromagnetic region SAF 1  and the ferromagnetic region FM may be inclined at a first angle θ j1  with respect to a reference surface SS perpendicular to the first direction D 1 , and the second junction surface  140 S 2  between the second synthetic antiferromagnetic region SAF 2  and the ferromagnetic region FM may be inclined at a second angle θ j2  with respect to the reference surface SS. Each of the first angle θ j1  and the second angle θ j2  may be greater than 30 degrees and may be, for example, greater than 30 degrees and less than 90 degrees. Accordingly, in some embodiments and as described with reference to  FIGS.  4 A and  4 B , it may be possible to reduce a current density applied to the conductive line CL to move the at least one lower magnetic domain wall DW_L in the ferromagnetic region FM into the first synthetic antiferromagnetic region SAF 1  or the second synthetic antiferromagnetic region SAF 2 . 
     According to the present embodiments, it may be possible to provide the magnetic memory device that is capable of reducing the current density for moving the magnetic domain wall in the magnetic track MTR including the synthetic antiferromagnetic structure. 
       FIGS.  7 A to  7 C  are cross-sectional views corresponding to the portion ‘A’ of  FIG.  2    to illustrate aspects of methods of manufacturing a magnetic memory device according to some embodiments of the inventive concepts. Hereinafter, the descriptions to the same features as mentioned with reference to  FIGS.  1  and  2    will be omitted for the purpose of ease and convenience in explanation. 
     Referring to  FIG.  7 A , a conductive line CL, a lower magnetic layer  110 , a spacer layer  120  and an upper magnetic layer  130  may be formed to extend in the first direction D 1 . The lower magnetic layer  110 , the spacer layer  120  and the upper magnetic layer  130  may be sequentially stacked on the conductive line CL in the third direction D 3 . 
     For example, the formation of the conductive line CL, the lower magnetic layer  110 , the spacer layer  120  and the upper magnetic layer  130  may include sequentially depositing a conductive layer, a first magnetic layer, a non-magnetic layer and a second magnetic layer, forming a first mask pattern M 1  on the second magnetic layer, and sequentially etching the second magnetic layer, the non-magnetic layer, the first magnetic layer and the conductive layer by using the first mask pattern M 1  as an etch mask. The conductive layer, the first magnetic layer, the non-magnetic layer and the second magnetic layer may be formed using a chemical vapor deposition (CVD) method and/or a physical vapor deposition (PVD) method and may be formed using, for example, a sputtering deposition method. The first mask pattern M 1  may have a line shape extending in the first direction D 1  and may be a photoresist pattern or a hard mask pattern. The second magnetic layer, the non-magnetic layer, the first magnetic layer and the conductive layer may be sequentially etched by, for example, an ion beam etching process. The upper magnetic layer  130 , the spacer layer  120 , the lower magnetic layer  110  and the conductive line CL may be formed by etching the second magnetic layer, the non-magnetic layer, the first magnetic layer and the conductive layer, respectively. The lower magnetic layer  110  and the upper magnetic layer  130  may be antiferromagnetically coupled to each other by the spacer layer  120 . 
     After the formation of the conductive line CL, the lower magnetic layer  110 , the spacer layer  120  and the upper magnetic layer  130 , the first mask pattern M 1  may be removed. The first mask pattern M 1  may be removed by, for example, an ashing process and/or a strip process. 
     Referring to  FIG.  7 B , a second mask pattern M 2  may be formed on the upper magnetic layer  130 . The second mask pattern M 2  may include an opening OP that exposes a portion of the upper magnetic layer  130 . The second mask pattern M 2  may be a photoresist pattern or a hard mask pattern. The second mask pattern M 2  may include a metal nitride and may include, for example, TaN. 
     An oxidation process may be performed on the upper magnetic layer  130 . The second mask pattern M 2  may be used as a mask of the oxidation process. The oxidation process may include, for example, an oxygen plasma treatment. 
     Referring to  FIG.  7 C , the portion of the upper magnetic layer  130  that is exposed by the opening OP of the second mask pattern M 2  may be oxidized by the oxidation process. Thus, a non-magnetic pattern  140  may be formed in the upper magnetic layer  130 . The non-magnetic pattern  140  may include a metal oxide. The non-magnetic pattern  140  may include a same magnetic element as a magnetic element in the upper magnetic layer  130  and may further include oxygen. 
     The spacer layer  120  may be used as an oxidation stop layer of the oxidation process. Thus, a portion  110 P of the lower magnetic layer  110 , which vertically overlaps with the non-magnetic pattern  140  (e.g., in the third direction D 3 ), may not be oxidized by the oxidation process but may maintain a ferromagnetic property. The non-magnetic pattern  140  may penetrate the upper magnetic layer  130  so as to be in contact with the spacer layer  120 . 
     After the formation of the non-magnetic pattern  140  by the oxidation process, the second mask pattern M 2  may be removed. The second mask pattern M 2  may be removed by, for example, an ashing process and/or a strip process. 
     The lower magnetic layer  110 , the spacer layer  120 , the upper magnetic layer  130  and the non-magnetic pattern  140  may constitute a magnetic track MTR. The conductive line CL and the magnetic track MTR may have line shapes extending in the first direction D 1 . 
     The magnetic track MTR may include synthetic antiferromagnetic regions SAF and a ferromagnetic region FM between the synthetic antiferromagnetic regions SAF. The synthetic antiferromagnetic regions SAF may be regions in which the lower magnetic layer  110  and the upper magnetic layer  130  are antiferromagnetically coupled to each other by the spacer layer  120 . The ferromagnetic region FM may include the non-magnetic pattern  140 , and the portion  110 P of the lower magnetic layer  110  which vertically overlaps with the non-magnetic pattern  140 . The magnetic track MTR may include a synthetic antiferromagnet-ferromagnet-synthetic antiferromagnet (SAF-FM-SAF) bi-lateral junction structure in which the synthetic antiferromagnetic regions SAF and the ferromagnetic region FM therebetween are joined to each other in the first direction D 1 . 
     Referring again to  FIG.  2   , a read/write unit  150  may be formed on a corresponding synthetic antiferromagnetic region SAF of the synthetic antiferromagnetic regions SAF of the magnetic track MTR. For example, the formation of the read/write unit  150  may include sequentially forming a tunnel insulating layer, a magnetic layer and an electrode layer on the magnetic track MTR, and etching the tunnel insulating layer, the magnetic layer and the electrode layer. A tunnel barrier pattern  152 , a magnetic pattern  154  and an electrode pattern  156  may be formed by etching the tunnel insulating layer, the magnetic layer and the electrode layer, respectively. 
       FIG.  8    is a plan view of  FIG.  7 B  to illustrate a method of manufacturing a magnetic memory device according to some embodiments of the inventive concepts. 
     Referring to  FIGS.  7 B and  8   , the second mask pattern M 2  may include a first inner sidewall M 2 _S 1  and a second inner sidewall M 2 _S 2 , which may be exposed by the opening OP. The first inner sidewall M 2 _S 1  and the second inner sidewall M 2 _S 2  may face each other in the first direction D 1 . In some embodiments, the first inner sidewall M 2 _S 1  may be inclined at a first angle θ j1  with respect to a reference surface SS perpendicular to the first direction D 1 , and the second inner sidewall M 2 _S 2  may be inclined at a second angle θ j2  with respect to the reference surface SS. Each of the first angle θ j1  and the second angle θ j2  may be greater than 30 degrees and may be, for example, greater than 30 degrees and less than 90 degrees. The second mask pattern M 2  may be used as the mask of the oxidation process, and thus side surfaces of the non-magnetic pattern  140  may be formed to be inclined with respect to the reference surface SS. As a result, as described with reference to  FIGS.  3  and  6   , the first junction surface  140 S 1  between the first synthetic antiferromagnetic region SAF 1  and the ferromagnetic region FM may be formed to be inclined at the first angle θ j1  with respect to the reference surface SS, and the second junction surface  140 S 2  between the second synthetic antiferromagnetic region SAF 2  and the ferromagnetic region FM may be formed to be inclined at the second angle θ j2  with respect to the reference surface SS. 
       FIG.  9    is a cross-sectional view illustrating a magnetic memory device according to some embodiments of the inventive concepts. Hereinafter, differences between the present embodiments and the above embodiments of  FIGS.  1  and  2    will be mainly described for the purpose of ease and convenience in explanation. 
     Referring to  FIG.  9   , the magnetic track MTR may include a plurality of non-magnetic patterns  140  in the upper magnetic layer  130 . The plurality of non-magnetic patterns  140  may be spaced apart from each other in the first direction D 1  in the upper magnetic layer  130 . In some embodiments, the upper magnetic domains D_U and the non-magnetic patterns  140  in the upper magnetic layer  130  may be alternately arranged in the first direction D 1 . Each of the plurality of non-magnetic patterns  140  may have a width  140 W in the first direction D 1 , and the width  140 W of each of the plurality of non-magnetic patterns  140  may be substantially equal to a width, in the first direction D 1 , of each of the upper magnetic domain walls DW_U in the upper magnetic layer  130 . Each of the plurality of non-magnetic patterns  140  may vertically overlap with a corresponding portion of the lower magnetic layer  110  in the third direction D 3  and, for example, may vertically overlap with a corresponding lower magnetic domain wall DW_L of the lower magnetic domain walls DW_L in the lower magnetic layer  110  (e.g., in the third direction D 3 ). 
     When a current flows in the first direction D 1  or the opposite direction to the first direction D 1  in the conductive line CL, the lower magnetic domain walls DW_L in the lower magnetic layer  110  may move in the first direction D 1 . Thus, magnetization directions  110 M of the lower magnetic domains D_L in the lower magnetic layer  110  may be reversed. Magnetization directions  130 M of the upper magnetic domains D_U in the upper magnetic layer  130  may be reversed to be antiferromagnetically coupled to the magnetization directions  110 M of the lower magnetic domains D_L, by the antiferromagnetic coupling between the lower magnetic layer  110  and the upper magnetic layer  130 . 
       FIG.  10    is a cross-sectional view illustrating a magnetic memory device according to some embodiments of the inventive concepts. Hereinafter, differences between the present embodiments and the above embodiments of  FIGS.  1  and  2    will be mainly described for the purpose of ease and convenience in explanation. 
     Referring to  FIG.  10   , the lower magnetic domains D_L in the lower magnetic layer  110  and the upper magnetic domains D_U in the upper magnetic layer  130  may have in-plane magnetic anisotropy (IMA). Each of the lower magnetic domains D_L in the lower magnetic layer  110  may have a magnetization direction  110 M parallel to an interface between the lower magnetic layer  110  and the spacer layer  120 , and magnetization directions  110 M of lower magnetic domains D_L adjacent directly to each other may be opposite to each other. Each of the lower magnetic domain walls DW_L may define a boundary between the adjacent lower magnetic domains D_L having the magnetization directions  110 M opposite to each other. Each of the upper magnetic domains D_U in the upper magnetic layer  130  may have a magnetization direction  130 M parallel to an interface between the upper magnetic layer  130  and the spacer layer  120 , and magnetization directions  130 M of upper magnetic domains D_U adjacent directly to each other may be opposite to each other. Each of the upper magnetic domain walls DW_U may define a boundary between the adjacent upper magnetic domains D_U having the magnetization directions  130 M opposite to each other. 
     The magnetic pattern  154  of the read/write unit  150  may have in-plane magnetic anisotropy (IMA). The magnetic pattern  154  may have a magnetization direction  154 M parallel to an interface between the magnetic pattern  154  and the tunnel barrier pattern  152 , and the magnetization direction  154 M of the magnetic pattern  154  may be fixed in one direction. The magnetization directions  130 M of the upper magnetic domains D_U in the upper magnetic layer  130  and the magnetization directions  110 M of the lower magnetic domains D_L in the lower magnetic layer  110  may be changeable to be parallel or antiparallel to the magnetization direction  154 M of the magnetic pattern  154 . 
     In some embodiments, each of the lower magnetic layer  110 , the upper magnetic layer  130  and the magnetic pattern  154  may include a ferromagnetic material, and the magnetic pattern  154  may further include an antiferromagnetic material for pinning or fixing a magnetization direction of the ferromagnetic material. 
     According to the inventive concepts, the magnetic track may include the synthetic antiferromagnet-ferromagnet-synthetic antiferromagnet (SAF-FM-SAF) bi-lateral junction structure in which the synthetic antiferromagnetic regions and the ferromagnetic region therebetween are joined to each other in the first direction. The ferromagnetic region may include the non-magnetic pattern and a portion of the lower magnetic layer which vertically overlaps with the non-magnetic pattern, and at least one lower magnetic domain wall may be arranged in the portion of the lower magnetic layer (e.g., in the ferromagnetic region). When an external magnetic field is applied to the magnetic track, the at least one lower magnetic domain wall in the ferromagnetic region may be trapped in the ferromagnetic region. Thus, it may be possible to minimize the influence of an external factor (e.g., the external magnetic field) on a position of a magnetic domain wall in the magnetic track, and the position of the magnetic domain wall in the magnetic track may be stably controlled by a current applied to the conductive line. As a result, it may be possible to provide the magnetic memory device capable of controlling more stably a position of a magnetic domain wall in the magnetic track including the synthetic antiferromagnetic structure. 
     In addition, a junction surface between each of the synthetic antiferromagnetic regions and the ferromagnetic region may be inclined at an angle with respect to the reference surface perpendicular to the first direction, and the angle may be greater than 30 degrees. In this case, it may be possible to reduce a current density applied to the conductive line to move the at least one lower magnetic domain wall in the ferromagnetic region into the synthetic antiferromagnetic regions. As a result, it may be possible to provide the magnetic memory device capable of reducing a current density for moving a magnetic domain wall in the magnetic track including the synthetic antiferromagnetic structure. 
     While some example embodiments of the inventive concepts have been particularly shown and described, it will be understood by one of ordinary skill in the art that variations in form and detail may be made therein without departing from the scope of the attached claims.