Page 310 - Read Online

Page 4 of 18 Deng et al. Microstructures 2023;3:2023044 https://dx.doi.org/10.20517/microstructures.2023.42

[57] [21]
Figure 3. The collinear (A) AFM structure of Mn ZnN and (B) the FIM structure of Mn Zn N .
3 3.19 0.77 0.94

5g 4g
Figure 4. The non-collinear (A) Γ and (B) Γ AFM structures of antiperovskites.

So far, five typical undoped antiperovskites displaying the non-collinear magnetic structures of Γ and Γ
4g
5g
types have been reported experimentally, including Mn NiN, Mn ZnN, Mn GaN, Mn AgN, and Mn SnN.
3
3
3
3
3
The magnetic structure of Mn NiN below 163 K, Mn ZnN between 140 K and 183 K, Mn GaN below 298 K,
3
3
3
and Mn AgN between 55 and 290 K belongs single-phase Γ type, corresponding to the magnetic moments
5g
3
0.98 μ /Mn (T = 77 K), 1.21 μ /Mn (T = 159 K), 1.17 μ /Mn (T = 4.2 K), and 3.1 μ /Mn (T = 4.2 K),
B
B
B
B
respectively . This type of magnetic structure has had an important impact on the mechanism exploration
[54]
of the NTE behavior, piezomagnetic effect, and barocaloric effect of antiperovskites. In addition, the
magnetic structures of Mn NiN between 163 K and 266 K, Mn AgN below 55 K and Mn SnN between
3
3
3
237 K and 357 K are composed of Γ and Γ types, showing the magnetic moments 0.8 μ /Mn at 250 K,
5g
4g
B
3.1 μ /Mn and 2.5 μ /Mn at 250 K at 4.2 K, respectively . It was suggested that the magnetic behavior of
[54]
B
B
antiperovskites is very sensitive to the differences of sample composition. In Mn Ni N , the magnetic
3
0.9
0.96
4g
structure is a combination of Γ and Γ symmetries below T = 264 K, and the moments undergo a rotation
5g
N
in the (111) plane upon warming . Moreover, for Mn Zn N, the sample fully transforms to the Γ phase
5g
[59]
96
3
upon cooling below 185 K, and the low-temperature collinear magnetic structure existing in Mn ZnN
3
disappears .
[20]
The non-collinear Γ AFM structure is also examined by both neutron diffraction and the correlated
5g
thermal expansion behavior in doped antiperovskites, such as Mn Cu (Ge, Sn) N, Mn Zn (Ge, Sn) N, and
3
x
x
3
1-x
1-x
5g
Mn Ga Sn N, etc. [5-22] . Particularly, the undoped Mn CuN does not display the Γ magnetic configuration.
3
1-x
x
3
As shown in Figure 5, a cubic structure with the Γ magnetic configuration was determined by neutron
5g
study in Mn Cu Ge N (x ≥ 0.15), which is suggested to be a key ingredient of a large magnetovolume effect
3
1-x
x
5g
in antiperovskites . Meanwhile, the NTE behavior determined by Γ magnetic order was also observed in
[18]