The topological Hall effect arises in magnetic materials with non-trivial spin arrangements and it has been suggested that they occur in non-cubic antiferromagnets. Here, the authors observe contributions to the anomalous Hall effect in the antiferromagnet Mn5Si3, which might be of topological origin.

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Large topological Hall effect in the non-collinear phase of an antiferromagnet

Magnetic properties of single crystalline Mn4Si7

The B2-ordered intermetallic magnetic compound FeRh exhibits a thermodynamically first-order phase transition in the vicinity of room temperature that makes it a highly intriguing subject for both fundamental and applied study. On heating through the transition the magnetic character changes from antiferromagnetic to ferromagnetic order with an accompanying large increase in the electrical conductivity and an abrupt expansion in the lattice structure. Accompanying these effects is a very large entropy change comprising both magnetic and lattice contributions. As well as being driven by temperature, these coupled phase transitions may be driven by the application or removal of a magnetic field, or, because of the extremely strong lattice-spin interactions present in this compound, by an applied strain (pressure), and combinations thereof. In addition to these driving factors, the transition temperature can also be tuned by both compositional and finite size effects. Building from historical work on bulk forms of FeRh, the effects of extrinsic and intrinsic parameter variation on the coupled magnetic, structural, and electronic phase transitions are reviewed here, with special attention directed to phenomena that manifest themselves in thin films. Overall, the rich manner in which the physical properties of FeRh change at the phase transition has potential for a wide range of technological applications in areas such as thermally-assisted magnetic recording media, CFC-free magnetic cooling, sensors for energy management, and novel spintronic devices.

https://iopscience.iop.org/article/10.1088/0022-3727/49/32/323002/pdf

Coupled magnetic, structural, and electronic phase transitions in FeRh

Anisotropy and metamagnetism in the RNi2Ge2 (R=Y, La–Nd, Sm–Lu) series

The Fe−Rh (Iron-Rhodium) system

The effect of quasi-hydrostatic pressures up to 100 kbar is investigated on the phase transitions of Fe1−xRhx alloys by resistivity measurements. The pressure dependence of the first order antiferromagnetic (AF) to ferromagnetic (FM) phase transformation temperature dTk/dp = 4.4 to 5 K/kbar. The pressure dependence of the second order FM to paramagnetic (PM) transition, i.e. that of the Curie-point is dTC/dp = −0.7 K/kbar. At about 60 kbar the thermal hysteresis diminishes, and above the range of the co-existence of three phases (AF—FM—PM) the pressure dependence of the AF—PM transition is characterized by dT/dp = 0.6 to 1.0 K/kbar. The AF—PM transition is investigated in an Ir-substituted alloy (Fe44Rh49.5Ir6.5) also, where dT/dp = 0.6 K/kbar.



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Pressure effects on magnetic phase transitions in FeRh and FeRhIr alloys

Pressure-induced antiferromagnetism in ferromagnetic Fe51.5Rh48.5 alloy

Magnetic phase transitions and electronic structure of the manganese silicides

Phase transitions into the ferro-magnetic and antiferromagnetic states for the stoichiometric FeRh alloy are discussed taking into account the self-consistent band structure calculations for the paramagnetic phase. A Peierls-type instability is one reason for the antiferromagnetic transition.

Electronic band structure and magnetic order in FeRh

Experiments indicate that the AF 1 phase in Mn 5 Si 3 can be suppressed by 5 kbar. Then, the AF 2 phase undergoes a transition to a ferromagnetic state. In (Mn 1−x Fe x ) 5 Si 3 samples a first-order metamagnetic transition in high magnetic fields at T < 62 K and the existence of a FM state with T c = 74 and 250 K have been observed

L. Vinokurova

Papers

Pressure effects on magnetic phase transitions in FeRh and FeRhIr alloys

Pressure-induced antiferromagnetism in ferromagnetic Fe51.5Rh48.5 alloy

Magnetic phase transitions and electronic structure of the manganese silicides

Electronic band structure and magnetic order in FeRh

Magnetic phase transitions in single crystals of Mn5Si3 and (Mn, Fe)5Si3