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Zhao et al. Microstructures 2023;3:2023022 https://dx.doi.org/10.20517/microstructures.2022.46 Page 5 of 9

Figure 2. (A-D) Magnetization curves for samples x = 0.18, 0.1, 0.08, and 0.04, respectively. (E) Curves of phase transition
temperature vs. manganese content x (blue squares and red dots indicate measurement by M-T and heat flow, respectively) and lattice
constant vs. manganese content x for the samples. (Taking x = 0.08 as an example, the fitting parameters obtained using the lebail
method to fit the XRD curve are: GOF = 1.47, Rp = 4.18, Rwp = 5.99). (F) The magnetization loop of x = 0.18. The inset shows the
enlarged plot at low fields.

still unknown. Previous studies have also shown that a ferromagnetic component perpendicular to the (111)
plane is allowed on both Mn and Pt atoms, except for the component in the (111) plane pointing in the
[112] direction in the magnetic structure of the triangular AFM phase . Furthermore, it has been pointed
[31]
out that the origin of this ferromagnetism may be because the third site of the colinear AFM phase generates
a net magnetic moment due to electron interactions at low temperatures of 100 K or even lower . In
[38]
contrast to the presence of net moments along the <111> direction, the magnetization curve of the single-
crystal material along the <111> direction did not show ferromagnetic behavior .
[34]

Except for the influence of magnetic fields on the first-order phase transitions, we explore the impact of
applied hydrostatic pressures. Heat flow data as a function of temperature are plotted under 0.1, 30, 60, and
90 MPa for x = 0.08 and x = 0.18 in Figure 3A and B, respectively. As the pressure increases, the
endothermic and exothermic peaks move toward the high-temperature region simultaneously. The peak
intensity has a small increase with pressure, while the peak width has a tendency to narrow, which is
especially obvious in the x = 0.18 sample. In addition, the thermal hysteresis at 0.1 MPa for the x = 0.08
sample is the same as that at x = 0.1, which is 19 K. However, the thermal hysteresis at atmospheric pressure
for x = 0.18 sample is 9 K and decreases to 5 K at 90 MPa with increasing pressure.

Entropy changes at the phase transition under constant pressure, ΔS , are determined by integrating the heat
P
) when pressure is increased from ambient
flow data. The pressure-induced entropy changes (ΔS P 0 →P
pressure (P ) to applied pressure (P) is defined as ΔS P 0 →P = ΔS - ΔS . Figure 3C and D show ΔS P 0 →P at the
0
P
P 0