Pressure Induced Magnetic Transition of Mn₃Ga_1-xAl_xC

X-ray Powder Diffraction Studies of Mn<SUB>3</SUB>Ga<SUB>0.97</SUB>Al<SUB>0.03</SUB>C in Magnetic Fields

“…3-6) The previous reports 4,6) and the our results show that this firstorder phase transition becomes dully with increasing x. Figure 3 shows the typical X-ray powder diffraction profiles of Mn 3 Ga 0:97 Al 0:03 C in 81:5 2 83:5 at several temperatures in a zero magnetic field.…”

“…This negative volume magnetostriction is consistent with the previous reports for Mn 3 Ga 1Àx Al x C with x ¼ 0, 0.03, and 0.05. 1,2,4,6) With further decreasing temperature, the shrinkage of a becomes less steep below T I{F . For T < 80 K, the lattice parameter a of the major AF phase is only shown in Fig.…”

“…4 and 5, no abrupt lattice expansion occurs until 80 K from higher temperature under a magnetic field of 4 T. According to the high-field magnetization data reported by Kamishima et al, the I phase is clearly distinguished from the F phase even under a high magnetic field of 17 T for Mn 3 Ga xÀ1 Al x C (0 x 0:05). [3][4][5]17) Furthermore, the T AF{I transition temperature decreases with increasing a magnetic fields, suggesting that the I phase becomes to be stable by applying magnetic field. Therefore, our structural result indicates that a field-induced magnetic phase transition from the AF to I phases occurs for 80 < T < 130 K. In addition, we found that a in the F and AF phases slightly decreases by applying magnetic field, though a in the I phase is not affected by magnetic field.…”

“…3,4) The substitution of Al for Ga in Mn 3 GaC reduces the volume and also induces the I phase in Mn 3 Ga 1Àx Al x C (0 < x 0:1). The transition temperatures vary with depending on the Al content.…”

“…The transition temperatures vary with depending on the Al content. [4][5][6] On the other hand, recently, it has been found that Mn 3 GaC shows a large magnetocaloric effect of approximately 15 Jkg À1 K À1 in a magnetic field change of 1-2 T, accompanied by the first-order magnetic phase transition. [7][8][9] Therefore, the compound also has been attracted interest from the point of view of application as a magnetic refrigeration material.…”