Search query: Tricritical behavior of two-dimensional intrinsic ferromagnetic 

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abstract: \mathrm{CrGeTe}}_{3} recently emerges as a new two dimensional (2D) ferromagnetic semiconductor that is promising for spintronic device applications. Unlike \mathrm{CrSiTe}}_{3} whose magnetism can be understood using the 2D Ising model, \mathrm{CrGeTe}}_{3} exhibits a smaller van der Waals gap and larger cleavage energy, which could lead to a transition of magnetic mechanism from 2D to 3D. To confirm this speculation, we investigate the critical behavior of \mathrm{CrGeTe}}_{3} around the second order paramagnetic ferromagnetic phase transition. We obtain the critical exponents estimated by several common experimental techniques including the modified Arrott plot, Kouvel Fisher method, and critical isotherm analysis, which show that the magnetism of \mathrm{CrGeTe}}_{3} follows the tricritical mean field model with the critical exponents \ensuremath{\beta} \ensuremath{\gamma} and \ensuremath{\delta} of $0.240\ifmmode\pm\else\textpm\fi{}0.006$ $1.000\ifmmode\pm\else\textpm\fi{}0.005$ and $5.070\ifmmode\pm\else\textpm\fi{}0.006$ respectively, at the Curie temperature of 67.9 K. We therefore suggest that the magnetic phase transition from 2D to 3D for \mathrm{CrGeTe}}_{3} should locate near a tricritical point. Our experiment provides a direct demonstration of the applicability of the tricritical mean field model to a 2D ferromagnetic semiconductor.
author_names: Guoming Lin

Houlong L Zhuang

X Luo

B Liu

F C Chen

J Yan

Y H Sun

J Zhou

W -J Lu

P Tong

Zhigao Sheng

Zhe Qu

W H Song

X B Zhu

Ya Ping Sun
title: Tricritical behavior of the two dimensional intrinsically ferromagnetic semiconductor CrGeTe 3
year: 2017

abstract: CrI3, which belongs to a rare category of two dimensional (2D) ferromagnetic semiconductors, is of great interest for spintronic device applications. Unlike CrCl3 whose magnetism presents a 2D Heisenberg behavior, CrI3 exhibits a larger van der Waals gap, smaller cleavage energy, and stronger magnetic anisotropy which could lead to a 3D magnetic characteristic. Hence, we investigate the critical behavior of CrI3 in the vicinity of magnetic transition. We use the modified Arrott plot and Kouvel Fisher method, and conduct critical isotherm analysis to estimate the critical exponents near the ferromagnetic phase transition. This shows that the magnetism of CrI3 follows the crossover behavior of a 3D Ising model with mean field type interactions where the critical exponents \b{eta} \gamma} and \delta} are 0.323, 0.835, and 3.585, respectively, at the Curie temperature of 64 K. We propose the crossover behavior can be attributed to the strong uniaxial anisotropy and inevitable interlayer coupling. Our experiment demonstrates the applicability of crossover behavior to a 2D ferromagnetic semiconductor.
author_names: Guoming Lin

X Luo

F C Chen

J Yan

J J Gao

Y H Sun

Wei Tong

P Tong

W -J Lu

Zhigao Sheng

W H Song

X B Zhu

Ya Ping Sun
title: Critical behavior of two dimensional intrinsically ferromagnetic semiconductor CrI3
year: 2018

abstract: The low field magnetization M and susceptibility {chi} are reported for the two layered Ruddleson Popper phase SrO(La{sub 1{minus}x}Sr{sub x}MnO{sub 3}{sub 2} for x=0.4 (denoted La{sub 1.2}Sr{sub 1.8}Mn{sub 2}O{sub 7} with an in plane magnetic easy axis. As T approaches the Curie temperature T{sub C}=116 K) on cooling, where the metal insulator transition occurs in zero field, {chi} diverges as H{sup {minus}1/{delta}{sup {prime} with {delta}=21{plus_minus}5. Also, near an extrinsic Curie transition attributed to {approximately}0.1{percent} volume fraction of intergrowths at T{sup {asterisk}=2.47 T{sub C} M scales as (1{minus}T/T){sup {beta} with {beta}=0.25{plus_minus}0.02. These results can be understood within the context of two dimensional XY models, and provide some perspective of the layered manganites. {copyright} {ital 1998} {ital The American Physical Society}
author_names: Samuel D Bader
title: Two Dimensional Intrinsic and Extrinsic Ferromagnetic Behavior of Layered La1.2Sr1.8Mn2O7 Single Crystals
year: 1998

abstract: A three dimensional breakdown behavior of the magnetic Bloch point domain wall (BP DW) propagation was investigated in a ferromagnetic nanowire with the variation of the external magnetic field by means of micromagnetic simulation. As magnetic field strength increases up to a threshold value, the BP DW velocity approaches a critical phase velocity of the spontaneously emitting spin wave (SW) where a Cherenkov type DW breakdown phenomenon is observed originating from an interaction between the spontaneously emitting SW and the BP DW. It is found that the velocity of the BP DW approaches a maximum value ~2000 m/s) due to the intrinsic reversal time of a BP spin texture. This suggests that although cylindrical ferromagnetic nanowires might be free from the two dimensional Walker breakdown phenomenon, there exists a Cherenkov type three dimensional breakdown behavior.
author_names: Xiao-Ping Ma

Jiangshan Zheng

Hong-Guang Piao

Daekyu Kim

Peter Fischer
title: Cherenkov type three dimensional breakdown behavior of the Bloch point domain wall motion in the cylindrical nanowire
year: 2020

abstract: In contrast to the current research on two dimensional (2D) materials, which is mainly focused on graphene and transition metal dichalcogenide like structures, studies on 2D transition metal oxides are rare. By using ab initio calculations along with Monte Carlo simulations and nonequilibrium Green's function method, we demonstrate that the transition metal oxide monolayer (ML) of Cr 2 O 3 is an ideal candidate for next generation spintronics applications. 2D Cr 2 O 3 has honeycomb kagome lattice, where the Dirac and strongly correlated fermions coexist around the Fermi level. Furthermore, the spin exchange coupling constant shows strong ferromagnetic (FM) interaction between Cr atoms. Cr 2 O 3 ML has a robust half metallic behavior with a large spin gap of ~3.9 eV and adequate Curie temperature. Interestingly, an intrinsic Ising FM characteristic is observed with a giant perpendicular magnetocrystalline anisotropy energy of ~0.9 meV. Most remarkably, nonequilibrium Green's function calculations reveal that the Cr 2 O 3 ML exhibits an excellent spin filtering effect.
author_names: Arqum Hashmi

Kenta Nakanishi

Muhammad Umar Farooq

Tomoya Ono
title: Ising ferromagnetism and robust half metallicity in two dimensional honeycomb kagome Cr2O3 layer
venue: npj 2D Materials and Applications
year: 2020

abstract: Using first principles calculations based on density functional theory, we study the magnetic and electronic properties of hole doped two dimensional InSe. Our simulations reveal that although 2D InSe is intrinsically non magnetic, a stable ferromagnetic phase appears for a wide range of hole densities. Interestingly, hole doping not only induces spontaneous magnetization but also half metallicity, and hole doped InSe, presenting one conducting and one insulating spin channel, could be highly promising for next generation spintronic nanodevices. The possibility to induce hole doping and a subsequent ferromagnetic order by intrinsic and extrinsic defects was also investigated. We found that In vacancy creates spin polarized states close to the valence band and leads to a p type behavior. Similar to In vacancies, group V atoms replacing Se atoms
author_names: K Iordanidou

Michel Houssa

Joseph Kioseoglou

Valeri V Afanas'ev

Andre Stesmans

Clas Persson
title: Hole doped two dimensional InSe for spintronic applications
year: 2020

abstract: We have investigated the critical behavior near the ferromagnetic transition of TlCo2S2 single crystals and the magnetic properties of Tl(Co0.95Ni0.05)2S2 by means of magnetization measurements. The obtained critical exponents b, g and d of TlCo2S2 could basically satisfy the scaling equations and are found very close to the prediction of the tricritical mean field theory. 5[Formula: see text] Ni doping drives the system to an antiferromagnetic ground state which is unstable to magnetic field, yielding metamagnetic transition. The possible existence of a tricritical point (TCP) in Tl(Co0.95Ni0.05)2S2 is also discussed.
author_names: Qianhui Mao

Jinhu Yang

Hangdong Wang

Bin Chen

Xiaodong Geng

Mengyang Pan

Minghu Fang
title: From tricritical ferromagnetism to metamagnetism in quasi two dimensional Tl(Co1 x Ni x )2S2 (x 0, 0.05)
venue: Journal of physics. Condensed matter an Institute of Physics journal
year: 2018

abstract: Exploring two dimensional materials with both ferromagnetic and ferroelectric properties is scientifically interesting and of great technical importance to magnetoelectric nanodevices, which may overcome the volatility in traditional electrical control approaches. In this work, using first principles calculations, we design a multiferroic van der Waals heterostructure by combining the Dirac half metal MnCl3 and ferroelectric monolayer CuInP2S6. Through the short term voltage stimulation provided by an external electric field, we can switch the polarized state of the CuInP2S6 layer to achieve nonvolatile electrical control behavior in the Dirac half metal MnCl3. When MnCl3 is combined with CuInP2S6 in the P| state, the Dirac cones of the spin up channel are destroyed due to the interfacial charge transfer, but the half metal characteristic is preserved. By contrast, MnCl3 transforms into a magnetic semiconductor upon contact with CuInP2S6 in the P| state. More importantly, this transformation process does not depend on complex external mechanisms, and nonvolatile control can be achieved only through the intrinsic properties, which is related to the broken spatial inversion symmetry of ferroelectricity. Therefore, nonvolatile modulation of the electronic properties in the Dirac half metal MnCl3 can be achieved through magnetoelectric coupling with a ferroelectric CuInP2S6 layer, suggesting a promising platform for exploring high efficiency nanodevices and nonvolatile storage.
author_names: Zhengfu Li

Baozeng Zhou
title: Theoretical investigation of nonvolatile electrical control behavior by ferroelectric polarization switching in two dimensional MnCl3/CuInP2S6 van der Waals heterostructures
year: 2020

abstract: Two dimensional (2D) materials with robust ferromagnetism have played a key role in realizing nextgeneration spin electronic devices, but many challenges remain, especially the lack of intrinsic ferromagnetic behavior in almost all 2D materials. Here, we highlight ultrathin Mn3O4 nanosheets as a new 2D ferromagnetic material with strong magnetocrystalline anisotropy. Magnetic measurements along the in plane and out of plane directions confirm that the out of plane direction is the easy axis. The 2D confined environment and Rashba type spin orbit coupling are thought to be responsible for the magnetocrystalline anisotropy. The robust ferromagnetism in 2D Mn3O4 nanosheets with magnetocrystalline anisotropy not only paves a new way for realizing the intrinsic ferromagnetic behavior in 2D materials but also provides a novel candidate for building next generation spin electronic devices.
author_names: Junchi Wu

Xu Peng

Yuqiao Guo

Haowen Zhou

Jiyin Zhao

Ke-Qin Ruan

Wangsheng Chu

Changzheng Wu
title: Ultrathin nanosheets of Mn3O4: A new two dimensional ferromagnetic material with strong magnetocrystalline anisotropy
year: 2018

abstract: Two dimensional (2D) nanosheets have shown great potential for their applications in next generation nanoelectronic devices. However, developing 2D nanosheets for next generation spintronics has been blocked due to their lack of robust intrinsic ferromagnetic behavior. Here, we highlight the robust ferromagnetic behavior in a 2D inorganic graphene like structure. d FeOOH ultrathin nanosheets, as a new 2D material, exhibit an unprecedented high saturation magnetization value of 7.5 emu g 1 at room temperature, which is the highest value among graphene and graphene analogues. Atomic scale topochemical transformation ensures the formation of 2D d FeOOH ultrathin nanosheets from intermediate Fe(OH)2 nanosheets. Moreover, the d FeOOH ultrathin nanosheet is found to be a semiconductor with a direct band gap of 2.2 eV. Owing to the advantages of robust ferromagnetism in semiconductors, d FeOOH ultrathin nanosheets are promising candidates for the construction of next generation spintronics.
author_names: Pengzuo Chen

Kun Xu

Xiuling Li

Yuqiao Guo

Dan Zhou

Jiyin Zhao

Xiaojun Wu

Changzheng Wu

Yi Xie
title: Ultrathin nanosheets of feroxyhyte: a new two dimensional material with robust ferromagnetic behavior
year: 2014