A temperature gradient in a ferromagnetic conductor can generate a transverse voltage drop perpendicular to both the magnetization and heat current. This anomalous Nernst e ect has been considered to be proportional to the magnetization 1-7 , and thus observed only in ferromagnets. Theoretically, however, the anomalous Nernst e ect provides a measure of the Berry curvature at the Fermi energy 8,9 , and so may be seen in magnets with no net magnetization. Here, we report the observation of a large anomalous Nernst e ect in the chiral antiferromagnet Mn 3 Sn (ref. 10). Despite a very small magnetization ∼0.002 µ B per Mn, the transverse Seebeck coe cient at zero magnetic field is ∼0.35 µV K −1 at room temperature and reaches ∼0.6 µV K −1 at 200 K, which is comparable to the maximum value known for a ferromagnetic metal. Our first-principles calculations reveal that this arises from a significantly enhanced Berry curvature associated with Weyl points near the Fermi energy 11 . As this e ect is geometrically convenient for thermoelectric power generation-it enables a lateral configuration of modules to cover a heat source 6 -these observations suggest that a new class of thermoelectric materials could be developed that exploit topological magnets to fabricate e cient, densely integrated thermopiles.Current intensive studies on thermally induced electron transport in ferromagnetic materials have opened various avenues for research on thermoelectricity and its application [12][13][14][15] . This trend has also triggered renewed interest in the anomalous Nernst effect (ANE) in ferromagnetic metals [3][4][5][6][7]15 , which is the spontaneous transverse voltage drop induced by heat current and is known to be proportional to magnetization (Fig. 1a). On the other hand, the recent Berry phase formulation of the transport properties has led to the discovery that a large anomalous Hall effect (AHE) may arise not only in ferromagnets, but in antiferromagnets and spin liquids, in which the magnetization is vanishingly small 10, [16][17][18][19][20][21][22] . As the first case in antiferromagnets, Mn 3 Sn has been experimentally found to exhibit a large AHE 10 . While the AHE is obtained by an integration of the Berry curvature for all of the occupied bands, the ANE is determined by the Berry curvature at E F (refs 8,9). Thus, the observation of a large AHE does not guarantee the observation of a large ANE. Furthermore, the ANE measurement should be highly useful to clarify the Berry curvature spectra near E F and to verify the possibility of the Weyl metal recently proposed for Mn 3 Sn (ref. 11).Mn 3 Sn has a hexagonal crystal structure with a space group of P6 3 /mmc (ref. 23). Mn atoms form a breathing type of kagome lattice in the ab-plane (Fig. 1b), and the Mn triangles constituting the kagome lattice are stacked on top along the c axis forming a tube of face-sharing octahedra. On cooling below the Néel temperature of 430 K, Mn magnetic moments of ∼3µ B lying in the ab-plane form a coplanar, chiral magnetic structure chara...

Reversible spin Hall effect comprising the "direct" and "inverse" spin Hall effects was successfully detected at room temperature. This experimental demonstration proves the fundamental relations called Onsager reciprocal relations between spin and charge currents. A platinum wire with a strong spin-orbit interaction is used not only as a spin current absorber but also as a spin current source in the present lateral structure specially designed for clear detection of both charge and spin accumulations via the spin-orbit interaction. The obtained spin Hall conductivity is much larger than the reported value of Aluminum wire because of the larger spin-orbit interaction.

We have studied theoretically and numerically dynamic properties of the vortex magnetic state in soft submicron ferromagnetic dots with variable thickness and diameter. To describe the vortex translation mode eigenfrequencies we applied the equation of motion for the vortex collective coordinates. We calculated the vortex restoring force with explicit account of magnetostatic interaction on the bases of the "rigid" vortex and two-vortices "side charges free" models. The latter model well explains the results of our micromagnetic numerical calculations. The translation mode eigenfrequency is inversely proportional to the vortex static initial susceptibility and lies in GHz range for submicron in-plane dot sizes. Introduction. Magnetic solitons and other non-linear magnetization distributions attract