23 research outputs found

    Anomalous Nernst effect in perpendicularly magnetised {\tau}-MnAl thin films

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    τ\tau-MnAl is interesting for spintronic applications as a ferromagnet with perpendicular magnetic anisotropy due to its high uniaxial magnetocrystalline anisotropy. Here we report on the anomalous Nernst effect of sputter deposited τ\tau-MnAl thin films. We demonstrate a robust anomalous Nernst effect at temperatures of 200 K and 300 K with a hysteresis similar to the anomalous Hall effect and the magnetisation of the material. The anomalous Nernst coefficient of (0.6±\pm0.24) μ\muV/K at 300 K is comparable to other perpendicular magnetic anisotropy thin films. Therefore τ\tau-MnAl is a promising candidate for spin-caloritronic research

    All Electrical Access to Topological Transport Features in Mn1.8_{1.8}PtSn Films

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    The presence of non-trivial magnetic topology can give rise to non-vanishing scalar spin chirality and consequently a topological Hall or Nernst effect. In turn, topological transport signals can serve as indicators for topological spin structures. This is particularly important in thin films or nanopatterned materials where the spin structure is not readily accessible. Conventionally, the topological response is determined by combining magnetotransport data with an independent magnetometry experiment. This approach is prone to introduce measurement artifacts. In this study, we report the observation of large topological Hall and Nernst effects in micropatterned thin films of Mn1.8_{1.8}PtSn below the spin reorientation temperature TSR190T_\mathrm{SR} \approx 190K. The magnitude of the topological Hall effect ρxyT=8\rho_\mathrm{xy}^\mathrm{T} = 8 nΩ\Omegam is close to the value reported in bulk Mn2_2PtSn, and the topological Nernst effect SxyT=115S_\mathrm{xy}^\mathrm{T} = 115 nV K1^{-1} measured in the same microstructure has a similar magnitude as reported for bulk MnGe (SxyT150S_\mathrm{xy}^\mathrm{T} \sim 150 nV K1^{-1}), the only other material where a topological Nernst was reported. We use our data as a model system to introduce a topological quantity, which allows to detect the presence of topological transport effects without the need for independent magnetometry data. Our approach thus enables the study of topological transport also in nano-patterned materials without detrimental magnetization related limitations.Comment: 8 pages, 3 figure

    Anomalous Hall effect and magnetoresistance in micro-ribbons of the magnetic Weyl semimetal candidate PrRhC2

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    PrRhC2 belongs to the rare-earth carbides family whose properties are of special interest among topological semimetals due to the simultaneous breaking of both inversion and time-reversal symmetry. The concomitant absence of both symmetries grants the possibility to tune the Weyl nodes chirality and to enhance topological effects like the chiral anomaly. In this work, we report on the synthesis and compare the magnetotransport measurements of a poly- and single crystalline PrRhC2 sample. Using a remarkable and sophisticated technique, the PrRhC2 single crystal is prepared via focused ion beam cutting from the polycrystalline material. Our magnetometric and specific heat analyses reveal a non-collinear antiferromagnetic state below 20K, as well as short-range magnetic correlations and/or magnetic fluctuations well above the onset of the magnetic transition. The transport measurements on the PrRhC2 single crystal display an electrical resistivity peak at 3K and an anomalous Hall effect below 6K indicative of a net magnetization component in the ordered state. Furthermore, we study the angular variation of magnetoresistivities as a function of the angle between the in-plane magnetic field and the injected electrical current. We find that both the transverse and the longitudinal resistivities exhibit fourfold angular dependencies due to higher-order terms in the resistivity tensor, consistent with the orthorhombic crystal symmetry of PrRhC2. Our experimental results may be interpreted as features of topological Weyl semimetallic behavior in the magnetotransport properties

    Saturation of the anomalous Hall effect at high magnetic fields in altermagnetic RuO2

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    Observations of the anomalous Hall effect in RuO2_2 and MnTe have demonstrated unconventional time-reversal symmetry breaking in the electronic structure of a recently identified new class of compensated collinear magnets, dubbed altermagnets. While in MnTe the unconventional anomalous Hall signal accompanied by a vanishing magnetization is observable at remanence, the anomalous Hall effect in RuO2_2 is excluded by symmetry for the N\'eel vector pointing along the zero-field [001] easy-axis. Guided by a symmetry analysis and ab initio calculations, a field-induced reorientation of the N\'eel vector from the easy-axis towards the [110] hard-axis was used to demonstrate the anomalous Hall signal in this altermagnet. We confirm the existence of an anomalous Hall effect in our RuO2_2 thin-film samples whose set of magnetic and magneto-transport characteristics is consistent with the earlier report. By performing our measurements at extreme magnetic fields up to 68 T, we reach saturation of the anomalous Hall signal at a field HcH_{\rm c} \simeq 55 T that was inaccessible in earlier studies, but is consistent with the expected N\'eel-vector reorientation field.Comment: 4 figure
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