Magnetotransport as a probe of phase transformations in metallic antiferromagnets: The case of UIrSi3

Abstract

The electrical resistance, Hall resistance and thermoelectric power of the Ising-like antiferromagnet UIrSi3 were measured as functions of temperature and magnetic field. We have observed that the unequivocally different characters of first-order and second-order magnetic phase transitions lead to distinctly different magnetotransport properties in the neighborhood of corresponding critical temperatures and magnetic fields, respectively. The magnetic contributions to the electrical and Hall resistivity in the antiferromagnetic state, and the polarized and normal regimes of paramagnetic state are driven by different underlying mechanisms. Results of detailed measurements of magnetotransport in the vicinity of the tricritical point reveal that the Hall-resistivity steps at phase transitions change polarity just at this point. The jumps in field dependences of specific heat, electrical resistivity, Hall resistivity and Seebeck coefficient at the first-order metamagnetic transitions indicate a Fermi surface reconstruction, which is characteristic of a magnetic-field induced Lifshitz transition. The presented results emphasize the usefulness of measurements of electrical-and thermaltransport properties as sensitive probes of magnetic phase transformations in antiferromagnets sometimes hardly detectable by other methods.

Record thermopower found in an IrMn-based spintronic stack

“…It was also found that magnon transport around the phase transition of antiferromagnetic NiO layer 35 facilitates magnon-mediated spin torque switching. Furthermore, antiferromagnet-based thermoelectrics [36][37][38][39] has seen a surge in interest lately. Here, we investigate the thermoelectric response of IrMn/CoFeB near the IrMn critical temperature.…”

Tricritical fluctuations and elastic properties of the Ising antiferromagnet UIrSi$_3$

“…For the measurements, we used pieces of a single crystal grown by the floating zone melting method in a commercial four-mirror optical furnace with halogen lamps, each 1kW (model FZ-T-4000-VPM-PC, Crystal Systems Corp., Japan), being part of the previous studies [16,17]. A polycrystalline precursor was synthesized by arc-melting from stoichiometric amounts of the pure elements U (3N, further treated by Solid-State Electrotransport [19,20]), Ir (4N), and Si (6N) in Ar (6N) protective atmosphere.…”

“…A large single crystal of the cylindrical shape with length 50 mm and diameter of 4 mm was obtained. The details of the preparation are discussed in [17]. The high quality and orientation of the single crystal were verified by the Laue method (see Fig.…”

“…Recently, we have studied in detail the magnetic, thermal, and transport properties of UIrSi 3 together with ab-initio calculation of the ground state [16,17] revealing the rich physics of the compound. However, the key question about the relation between the magnetic and crystal structure remained unanswered.…”

Magnetic phase diagram of the antiferromagnet U2Rh2Pb

“…In previously studied AFM materials [41][42][43], the disappearance of the hysteresis has been considered as one of the signatures of a tricritical point (TCP) in the phase diagram which separates first-and second-order AFM transitions and exhibiting Ising-type anisotropy [42,[44][45][46][47]. This supports the existence of TCP in U2Rh2Pb around Ttc = 13 K and µ0Htc = 4 T. It should be pointed out that TCP is an inherent feature of a broad class of antiferromagnets, in which the metamagnetic transition at low temperatures is of the first-order type and magnetic critical point in zero field is of the second-order type, and hence does now imply any temperature variations of magnetic interactions [48].…”