Magnetism and magnetic structures of PrMn2Ge2-xSix

被引:15
作者
Wang, J. L. [1 ,2 ,3 ]
Campbell, S. J. [3 ]
Hofmann, M. [4 ]
Kennedy, S. J. [1 ]
Zeng, R. [2 ]
Din, M. F. Md [2 ]
Dou, S. X. [2 ]
Arulraj, A. [5 ]
Stusser, N. [5 ]
机构
[1] Australian Nucl Sci & Technol Org, Bragg Inst, Lucas Heights, NSW 2234, Australia
[2] Univ Wollongong, Inst Superconduct & Elect Mat, Wollongong, NSW 2522, Australia
[3] Univ New S Wales, Australian Def Force Acad, Sch Phys Environm & Math Sci, Canberra, ACT 2600, Australia
[4] Tech Univ Munich, FRM 2, D-85747 Garching, Germany
[5] HZB, BER 2, D-14109 Berlin, Germany
基金
澳大利亚研究理事会;
关键词
NEUTRON-DIFFRACTION; FERROMAGNETISM; TRANSITIONS; BEHAVIOR; MN;
D O I
10.1088/0953-8984/25/38/386003
中图分类号
O469 [凝聚态物理学];
学科分类号
070205 ;
摘要
The structural and magnetic properties of seven PrMn2Ge2-xSix compounds with Si concentrations in the range x = 0.0-2.0 have been investigated by x-ray diffraction, magnetic (5-350 K), differential scanning calorimetry (300-500 K) and neutron diffraction (3-480 K) measurements. Replacement of Ge by Si leads to a contraction of the unit cell and significant modifications to the magnetic states-a crossover from ferromagnetism at room temperature for Ge-rich compounds to antiferromagnetism for Si-rich compounds. The compositional dependence of the room temperature lattice parameters exhibits non-linear behaviour around x = 1.2, reflecting the presence of magnetovolume effects. Re-entrant ferromagnetism has been observed in both PrMn2Ge1.0Si1.0 and PrMn2Ge0.8Si1.2 compounds with co-existence of canted ferromagnetism and canted antiferromagnetism detected, with both compounds exhibiting a larger unit cell volume in the canted Fmc state than in the canted AFmc. Combined with earlier studies of this system, the magnetic phase diagram has been constructed over the full range of PrMn2Ge2-xSix compositions (x = 0.0-2.0) and over the temperature range of interest (T = 3-480 K). In common with other systems in the RMn2X2 series, the overall magnetic behaviour of PrMn2Ge2-xSix compounds is governed by the strong dependence of the magnetic couplings on the Mn-Mn spacing within the ab-plane. Both total manganese moment mu(Mn)(tot) and in-plane manganese moment mu(Mn)(ab) at 5 K are found to decrease with increasing Si content, which can be ascribed to the reduction of Mn-Mn separation distance and stronger Si-Mn hybridization compared with Ge-Mn hybridization. Pr site ferromagnetic ordering occurs for x < 1.6 below T-C(Pr) .
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页数:13
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