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Applied Physics Lettersc,,/garO
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FIG. 1. (a) Schematic showing the reversible TCSMS; M represents the net spontaneous magnetization. (b) Image of a polycrystalline (powder) CaMn0.95Sb0.05O3 sample (c)Changes in the spontaneous magnetization of a polycrystalline CaMn0.95Sb0.05O3 sample with repeated temperature sweeps at 0 T. (d–f) Magnetic field dependence of magnetization at 80, 50, and 10 K, respectively.

2HhDRc(AFM)
transitionat the N!eel temperature (T ! 125 K). The AFM
sweeps, without the application of an external magnetic field. Theu
2:
01
sample was prepared by a conventional solid-state reaction. Prior toordering shows weak ferromagnetism because of the spin canting
this measurement, a magnetic poling treatment with a magnetic field
induced by the Dzyaloshinskii–Moriya interaction. Partial substi(g6(hp 2HFof 0.1 T (field-cooled from 300 K to 10 K) was carried out. Reversible
tution of pentavalent cations such as V , Nb , Ta , and Sb atspontaneous magnetization switching was observed upon heating and
the B-site leads to an anomalous magnetization reversal in a maghcooling. The values of spontaneous magnetization were 0.016 l /f.u.
(Fig. S1). Substitution of pentavalent
netic-field-cooling processside and #0.008 l /f.u. for the negative side. These valcations results in electron doping into the manganese ions.
pt
m reversal foruesthewerepositivept
retained forfive cycles ($1150 min). A temperature hystereHowever, the microscopic mechanismof magnetization
sis of $2 K was observed between the data collected during heating
and the function of spontaneous magnetization remain unclear.
p study,
fwe demonstrate that polycrystalline and cooling“(Fig. S2).pc
Figures 1(d)–1(f) show the magnetic field depenIn the present
dence of magnetization at 80, 50, and 10 K. Simple weak ferromagnetic
CaMn Sb O exhibits reversible TCSMS in the absence of an
external magnetic field [Figs. 1(a) andThe reproducibilityof thebehavior
was observed
each temperature. Notethat magnetization
GRRO,R 1(b)].FDM
RNGNJS
B IO
A atJHLSPENMCDP
reversible TCSMS is high even in positive- and negative-bias magnetic
became zero at 50 K for Fig. 1(c) in the temperature sweep process,fields. The neutron powder diffraction study indicates that two AFM
while the M–H hysteresis curve at 50 K in Fig. 1(d) showed finite magocAFM—coexist and that their ratio netization. This behavior differs from that of common ferrimagnets,
phases—G-type
AFM and A-type
N

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3changes during the magnetization switching. Density function theory(DFT) calculations corroborate that both the G-type and A-type AFM
phases exhibit weak ferromagnetism because of theDzyaloshinskii–Moriya interaction. The reversible TCSMS is accompanied by a change in the ratio of the AFM phases whose spontaneousmagnetization should be oriented in the opposite direction.
Figure 1(c) shows the change in spontaneous magnetization of apolycrystalline CaMn0.95Sb0.05O3 sample with repeated temperature#"   #  !  which exhibit antiferromagnetic behavior at their compensation temperatures. This extraordinary property is simply explained by assuming a two-phase model described later. The reversible TCSMS wasobserved even in bias magnetic fields, as shown in Fig. 2. The strengthsof the applied bias magnetic fields were þ0.1 and #0.1 T, which werelower than the coercive field of $0.25 T. The spontaneous magnetization shifted toward the applied magnetic field and was retained
through the cyclic process.

Appl. Phys. Lett. 117, 112404 (2020); doi: 10.1063/5.0017506

117, 112404-2

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3KAZUHIRO NAWA et al.

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T ¼ 300 K
Pr112bPr2
8aRu
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Al
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0.4395(5)0.1098(6)0.8718(5)0.2936(6)00.1098(6)00.2936(6)1=40.1098(6)1=40.2936(6)0.017(2)0.001(3)0.0042(8)0.010(4)T ¼ 10 K
Pr1
Pr2
RuAl0.4393(5)0.1087(5)0.8696(4)0.2935(5)00.1087(5)00.2935(5)1=40.1087(5)1=40.2935(5)0.0078(18)0.002(2)0.0046(7)0.005(3),12b
8a12b8a,/),

cw
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10 K

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Bragg position

2
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3

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20000RE

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Ru

wavelength of ! ¼ 2:4395 Å to study the magnetic reﬂectionsin the low-Q region in detail. Hence, we could not obtainreﬂections in the high-Q region. Therefore, the isotropic
atomic displacement parameter Uiso was not reliably
determined in the present Rietveld analysis. Table I summarizes the reﬁned crystallographic parameters.
At lower temperatures, magnetic reﬂections start todevelop and become clearly visible at 3 and 1.5 K. The inset Fig. 4. (Color online) (a) Rietveld analysis result for T ¼ 1:5 K data
2. inColormapsof ofscattering
along the K direction measured at (a)–(c) 0.3 K and (d)–(f)of Fig. 4(a) shows a magniﬁed view of the diﬀractionFIG.
shown
Fig. 3. contour
The calculated
positions
nuclear and intensities
magnetic
indicatedby the green
ticks. 4.0
The bottom
represents the lattice unit), and the L range is indicated above each figure. The sp
patterns in the lower-2" range measured at 10 and 1.5
K. reﬂections
integratedforaretheH range
below
r.l.u.line(reciprocal
Clearly, the 1.5 K data show extra reﬂections that were not diﬀerence. The inset shows a magniﬁed view for 2" < 50°. (b) Schematicand (b),(c),proposed(e), (f)20.96
The intensities from the elastic signals appear as the background be(a), (d)illustration
Ei = of9.71
the magneticstructurein thepresentmeV.
study. For
observed at 10 K. The results are consistent with the DC simplicity,
the centering translation is omitted and only half of the unit cell is(b), (c),(e), (f)2 meV. (g)–(i) Color contour maps of scattering intensities simulated by applying the RPA to antiferr
magnetic susceptibility measurement, where the transition
illustrated. (c) Spatial modulation of the total Pr 3+ moment in orbit 1 for thewas observed at Tc ’ 3:8 K at a low external magnetic ﬁeld.
presentlyproposedEach!2 IR. spectrum includes the contribution of dispersive modes from an antibound/bound spinon pair,spin-1/2
chains.
Magnetic satellite reﬂections were observed in the vicinityof the nuclear reﬂections. This clearly indicates thatthe
the black dashed curves.
magnetic ordering is neither simple ferromagnetic nor the irreducible representations (IRs) for the k-subgroup were
antiferromagnetic, but incommensurately  modulated with a calculated and are listed in Table II. All the IRs are onelong modulation period. Under the cubic symmetry, the eight dimensional. Landau theory for the second-order phasesatellite reﬂections at ð##; ##; ##Þ around the 110 nuclear transition requires a single IR to be selected in the ordereda smalldispersion
is ofpresent
alongtothe L direction,[− 0.5 0.5]. The differences between th
peak appear as three reﬂections at Q1 ¼ jð1 % #; 1 % #; ##Þj,Second,
phase, andhence linear
combinations
BVs belonging
IR haveto be taken
account
in principle. couplings
InQ2 ¼ jð1 # #; 1 & #; # or & #Þj, and Q3 ¼ jð1 þ #; 1indicatingþ #; the samethe
presenceof into
weakinterchainalong
0.3 and 2.6 K are also evident in the i##Þj in the powder diﬀraction pattern. Indeed, this is the addition, BVs for the diﬀerent orbits can be selected
the c axis. Figure 4 shows the intensity maps along the L
shown in Figs. 5(a) and 5(b). These difcase for the positions and the number of magnetic satellite independently. Therefore, the initial model structure should
The
maximumof inthelower
energy boundaries ofcoexistence of spin-1 excitations, which
reﬂections visible in the present powder pattern. Thus,direction.
the be linear
combinationsof the BVs
an IR,
with independent
magnetic propagation vector q is most likely to be alongthe
the continuum
phases (and amplitudes)
for diﬀerent
However,theoccurs near
L = 0orbits.
for K= [0.20,0.30], while
antiferromagnetic chains in addition to thð1; 1; 1Þ direction, i.e., q ¼ ð#; #; #Þ. From the peak position, number of magnetic reﬂections observed experimentally is
the minimumnear
L = 0in thisforgeneral
K =model.
[0.70, 0.80]. This
at 0.3 K. For a fixed K, the dispersion in
not enough tooccurs
reﬁne all theparameters
we estimate # ’ 0:066 (r.l.u.). This corresponds to moduwe further indicatesassume that a thatsingle theBV isinterchain
selected for couplings J ′lation with a length of ∼90 Å. We therefore conclude thata Therefore,
reverseddispersion
the L range where the lower energy bounvery interesting long-wavelength incommensurate magnetic each orbit for the sake of simplicity. Using this assumption, aare formed
along
diagonal
direction.
Theasdispersion canuum become small. This suggests that intrial function
for theaspin
structure analysis
may be written
structure is formed in this Pr compound.
To ﬁnd a possible microscopic model for the magnetic
also be confirmedCfrom
the integrated intensities shown inare relevant for the formation of spin-1i20–22)
j%i½q)ðR
þR
Þþ2$%
*jl
istructure, magnetic representation analysis
was perSðl; j;5(b).
iÞ ¼ Thef nðiÞpeakeþ c:c:g;Figs. 5(a) andposition
shifts to lower energies
discuss in Sec. V.
2formed using the paramagnetic space group I2 3 and theD -on og
p1,SiteK. Makino et al.
70000

nwc o

Atom,

Letters

Table I. Reﬁned atomic positions at 300 and 10 K. The space group isI21 3. Fifty-eight reﬂections were used in the reﬁnement with nine adjustableparameters. For T ¼ 300 K, the lattice constant, the cell volume, and thecalculated density of the cell are a ¼ 9:79542ð4Þ Å, V ¼ 939:874ð7Þ Å3, and& ¼ 7:1596 g=cm3, respectively. The R-factors are Rp ¼ 18:9%, Rwp ¼
15:5%, Rexpt ¼ 5:9%, and ' 2 ¼ 7:1. For T ¼ 10 K, a ¼ 9:77736ð3Þ Å, V ¼
934:683ð6Þ Å3, and & ¼ 7:1994 g=cm3. The R-factors are Rp ¼ 16:2%,Rwp ¼ 13:7%, Rexpt ¼ 3:8%, and ' 2 ¼ 13:4.

cwuwc oJ. Phys. Soc. Jpn. 85, 073705 (2016)

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L atforKthe=magnetic[0.20,0.30]at the[Fig.
5(a)] but shifts todetermined magnetic wave vector q ¼ ð#; #; #Þ. Forwith
the decreasing
where Sðl; j; iÞ stands
momentjth atomj
symmetry operations of the k-subgroup with q ¼ ð#; #;#Þ, of energies
the ith orbit inwith
the lthdecreasing
unit cell. nðiÞisLtheatn thK
BV=for [0.70,thehigher0.80]. The
the crystallographically equivalent Pr1(12b) sites become jth atom of the ith orbit and is given in Table II whereas, Ci
above
twofeaturesarealsoobservedintheinequivalent, and two orbits (orbits 1 and 2) are formed. and %i are the amplitude and phase of the BVs for the atomsspin excitation
Similarly, the Pr2(8a) sites split into two orbits (orbits 3spectrum
and in theof
ith Csorbit,respectively.
stands for evidencecomplexfor the sig2 CuCl
4 . Thisc.c.provides
4). Orbits 1, 2, and 4 contain three atoms, which are conjugate. Since we assume that the magnetic structurenificance
oftointerchain
thef anisotropic
triangularsymmetrically related by threefold rotation around the [111]belongsa single IR, wecouplings
select all fourin
BVs,
nð1Þ ; nð2Þ ;axis. Orbit 3 has only one atom. The basis vectors (BVs)
offrom5 Cl
thoselatticeofReO
nð3Þ ; Canð4Þ3g,2 . belonging to a single IR. For allp
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0.6

0.8

k=1

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84-0.4h (r.l.u.)

Because the spin excitations reflectcharacter, the excitations should be intertheir pairs. Indeed, Kohno et al. proposed
tinuum and sharp dispersive modes, such
Cs2 CuCl4 , can coexist in an ATLAF [45induced by spinons propagating along echain, while the dispersive modes are dspinon pair. A single spinon cannot propa
because of the competition between int
On the other hand, the propagation of a ppossible and leads to a gain in the kinetic073705-3
The PhysicalSociety of Japan©2016
While the intensities ofthecontinuum
are almost temperature independent, the intensities of the dispersive modes
increase as the temperature is lowered to 0.3 K. For instance,in the dispersion for the K range of [0.20, 0.30], a sharp
dispersion becomes prominent at the L ranges of [− 1.0, − 0.5]
and [0.5, 1.0], as indicated by Figs. 4(a) and 4(e). An intensity
increase at 0.3 K is also observed in the K range of [0.70,0.80]. However, the increase occurs at a different L range of12hω = 181.5meV

0.6

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