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Page 12 of 18 Deng et al. Microstructures 2023;3:2023044 https://dx.doi.org/10.20517/microstructures.2023.42

4g
[29]
and Γ magnetic phases . In 2019, Zhao et al. experimentally observed the anomalous Hall effect in the
4g
non-collinear AFM Mn Ni Cu N, which is attributed to the nonzero Berry curvature of the Γ magnetic
1-x
3
x
[30]
phase in momentum space [Figure 9C] . The research on the anomalous Hall effect of antiperovskites is
attracting widespread attention for novel spintronic applications.
Piezomagnetic/baromagnetic effects in antiperovskites
The piezomagnetic effect has been reported in non-collinear AFM antiperovskites [23,33] . In 2008,
Lukashev et al. predicted that the non-collinear magnetic structure of Mn GaN can be controlled by a small
3
[23]
applied biaxial strain [Figure 10A] . Figure 10B shows the net magnetic moment of Mn GaN and the
3
rotational angle of the magnetic moment of Mn atoms as a function of axial strain. It can be seen that the
atomic magnetic moment rotates when the strain is applied. This piezomagnetic effect is linear and displays
magnetization reversal with the applied strain. As the compressive strain is 1%, the magnetization is about
0.04 μ /f.u. Therefore, this property can be utilized for the application of the magnetoelectric effect, such as a
B
combination of piezomagnetic and piezoelectric phases or a combination of magnetostrictive and
piezoelectric phases [31,32] . In addition, Zemen et al. theoretically performed a systematic study of the
piezomagnetic effect in nine cubic antiperovskites Mn XN (X = Rh, Pd, Ag, Co, Ni, Zn, Ga, In, Sn),
3
revealing an extraordinarily large piezomagnetic effect in Mn SnN at room temperature . Boldrin et al.
[33]
3
demonstrate experimentally that a giant piezomagnetic effect is indeed manifest in the AFM antiperovskite
Mn NiN .
[34]
3
In 2016, the baromagnetic effect of Mn Ga N was determined by both neutron diffraction analysis and
3
0.95
0.94
magnetic measurements . Interestingly, Mn Ga N displays a new tetragonal non-coplanar magnetic
[35]
3
0.94
0.95
structure M-1 below 50 K, which is in coexistence with Γ spin configuration under atmospheric pressure.
5g
As shown in Figure 10C and D, the sample exhibits the piezomagnetic effect. When the applied pressure is
750 MPa at 130 K, the magnetic phase transition from M-1 to Γ AFM appears, generating the
5g
piezomagnetic characteristic of 0.63 μ /f.u. Combined with the refined results of neutron diffraction, the
B
change of Mn-Mn distance and spin rearrangement caused by pressure is considered to be the trigger of the
observed baromagnetic effect.
Magnetocaloric effect
[36]
The magnetocaloric effect of antiperovskites was primarily reported in Mn GaC . The collinear AFM-
3
intermediate magnetic transition of Mn GaC showing a first-order characteristic can be controlled by an
3
external magnetic field, generating the magnetocaloric effect. Figure 11A shows the temperature
dependence of the maximum value of magnetic entropy change ΔS . The peak of ΔS reaches 17 J/(kg·K)
mag
mag
when the external magnetic field is 10 kOe, and the peak value broadens to a "platform" shape with further
increase of the magnetic field. In addition, by introducing C vacancies, the magnetic properties of Mn GaC
3
were changed, thereby affecting the magnetocaloric effect . The magnetic entropy of Mn GaC decreased
[37]
0.78
3
to 3.7 J/kg·K under a 5 T magnetic field. In Mn Co GaC, Co doping can reduce the first-order phase
x
3-x
transition temperature from 164 K to 100 K without a significant decrease of magnetic entropy and realize
[38]
the magnetocaloric effect covering a wider temperature range (50-160 K) .
A large magnetic entropy change was observed in Mn Cu N 0.96 [39] [Figure 11B]. By introducing vacancies,
3
0.89
the onset of the FIM-PM transition is slightly reduced from 150 K of Mn CuN to 147.7 K of Mn Cu N ,
0.89
3
0.96
3
and a new non-coplanar FIM structure with an orthorhombic symmetry was determined. The total entropy
change of Mn Cu N obtained by DSC is about 60 J/kg·K, while the maximum magnetic entropy change
0.96
3
0.89
ΔS is 13.52 J/kg·K under a magnetic field of 50 kOe near the temperature of FIM-PM transition. Neutron
mag
diffraction results indicate that the magnetic entropy change of Mn Cu N is caused by the magnetic
0.89
3
0.96
transition from the AFM to the FM component in the tetragonal phase and the phase transition from cubic
to tetragonal under a magnetic field.