Especially sse in ferromagnetic insulators fi 1114 has attracted much attention because a pure spin current can be generatedwithoutanycharge. Room temperature and lowfield resonant enhancement of spin. Pdf the spin seebeck effect sse consists in the generation of a spin current by a temperature gradient applied in a magnetic film. The spin current propagates across the epitaxial, antiferromagnetic insulating nio layer, before being detected in the pt layer by the inverse spin hall effect. Spin colossal magnetoresistance in an antiferromagnetic. Spin seebeck effect from antiferromagnetic magnons and. Then, the spin information transports in the spin superfluid state, which can propagate to the right pt electrode and be detected by voltage measurement across the pt strip via the inverse spin. Observation of the spinseebeck effect in a ferromagnetic. This is, like ferromagnetism and ferrimagnetism, a manifestation of ordered magnetism generally, antiferromagnetic order may exist at sufficiently low. It was reported that a spin current perpendicular to an applied temperature gradient can be generated in a ferromagnetic metal fmm by the transverse sse. Antiferromagnetic spin seebeck effect american physical society. Abstract we report on the observation of the longitudinal spin seebeck effect in both antiferromagnetic and paramagnetic insulators.
We report on the observation of the spin seebeck effect in antiferromagnetic mnf2. We report on the observation of the spin seebeck effect in antiferromagnetic mnf 2. Fe 2 o 3 and magnetite fe 3 o 4 thin films by means of the spin seebeck effect. By analogy with its charge counterpart, this effect. We develop a theory of the spin seebeck effect sse in paramagnets as well as in antiferromagnets at elevated temperatures where the classical limit of the fluctuationdissipation theorem is. Magnon diffusion theory for the spin seebeck effect in.
Record thermopower found in an irmnbased spintronic stack. Based on this finding, an interesting type of spin field effect. By using a microscale onchip local heater, it is possible to generate a large thermal gradient confined to the chip surface without a large increase in the total sample temperature. Valleyspin seebeck effect in heavy groupiv monolayers. The antiparallel alignment is the result of superexchange of spin energy within the material 5. A device scale onchip heater is deposited on a bilayer of. The low temperature 280 k and high magnetic field up to 140 koe regime is explored. Distinguishing antiferromagnetic spin sublattices via the spin.
Experimental signatures of spin superfluid ground state in. Pdf theory of the spin seebeck effect in antiferromagnets. It has been shown that insulating afms are able to exhibit spin transport 14 and, moreover, thermal magnon currents induced by the spin seebeck effect sse 1511, 16, when driven into the spinflop state 1719. Request pdf distinguishing antiferromagnetic spin sublattices via the spin seebeck effect antiferromagnets are beneficial for future. With the spin seebeck effect in mind, we restrict this paper to ferromagnetic. Using pt as a spin detector layer it is possible to measure thermally. The sse is usually detected by an electric voltage generated in a metallic layer in contact with the magnetic film resulting from the conversion of the spin current into charge current by means of the inverse spin hall effect. A device scale onchip heater is deposited on a bilayer of mnf2 110 30nmpt 4 nm grown by molecular beam epitaxy on a mgf2110 substrate.
Resonant enhancement of spin seebeck effect sse due to phonons was recently discovered in y fe o yig. Giant localised spinpeltier effect due to ultrafast. In simple ferromagnetic insulators there is only one magnon mode, while in twosublattice antiferromagnetic insulators afis there are two modes, which carry spin currents in opposite directions. Do the voltage signals originate from coherent spin pumping at the mnf 2 pt interface or the incoherent spin seebeck effect 34, 35 induced by a temperature gradient. As an approach to power technologies in the current internetofthings era, onchip energy harvesting is highly attractive, and to be effective, demands thin film materials with large seebeck coefficients. The thickness of the nio layer is varied from 0 to 10 nm. Here, the spin seebeck effect is observed in a ferromagnetic semiconductor, gamnas, which allows flexible design of the magnetization directions, a larger spin polarization, and measurements. In materials that exhibit antiferromagnetism, the magnetic moments of atoms or molecules, usually related to the spins of electrons, align in a regular pattern with neighboring spins on different sublattices pointing in opposite directions. The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple. But gaining direct access to their antiferromagnetic order and identifying the properties of individual magnetic sublattices, especially in thin films and smallscale devices, remains a formidable challenge. Here, we show that antiferromagnetic vdw bilayers can be made half metallic, in which electrons of singular spin are metallic but those of the opposite spin are insulating, leading to 100% spin polarized conduction electrons.
The spins are injected into the antiferromagnetic cr 2 o 3 thin films from the local joule heating on the pt strip via spin seebeck effect 2426. The inverse spin hall effect converts the injected spin current into a transverse charge voltage, thereby producing. Paper open access spin valley filter effect and seebeck effect in a silicene based antiferromagnetic ferromagnetic junction to cite this article. In this study, the first instance of the formation of a spin thermopile via a simplified and straightforward method which utilizes two distinct characteristics of antiferromagnetic irmn is reported. The sse is usually detected by an electric voltage generated in a metallic layer in contact with the magnetic film resulting from the conversion. The observed spinseebeck signal here is a few orders. Bipolar magnetic semiconductor properties and spin. A device scale onchip heater is deposited on a bilayer of mnf2 110 30 nmpt 4 nm grown by molecular beam epitaxy on a mgf2 110 substrate. The generation of spin currents by thermal gradients applied to a magnetic film is known as the spin seebeck effect sse. Spin thermophysics offer a wide plethora of phenomena to be exploited at the nanoscale, such as the spin seebeck 2 and its inverse the spin peltier effect spe 3,4, i. In the ptyig bilayers, the temperature gradient applied to the yig stimulates dynamic spin injection into the pt, which generates an inverse spin hall voltage in the pt. The spin seebeck effect sse allows for the generation of thermally excited spin waves and thus enables one to probe a broad frequency distribution of magnon spectra 1. When the spin orientation on one side of the zgnr is inverted antiferromagnetic afm ordering, the transmission probabilities near the fermi level are greatly suppressed, and a.
Vk is observed on the yig film within a broad peak around 20 k. Scilit article record thermopower found in an irmn. Electrically induced 2d halfmetallic antiferromagnets and. Influence of thickness and interface on the lowtemperature enhancement of the spin seebeck effect in yig films erjia guo,1,2 joel cramer,1 andreas kehlberger,1 ciaran a. We work with correlated complex oxides, and more recently also with topological semimetals. Furthermore, the magnon spin current at the interface of irmncofeb can contribute to the spin seebeck effect as studied previously 28,29,31,33,66,67, but the electric voltage due to this effect. Spin seebeck effect in the antiferromagnet nickel oxide at. Thermoelectric devices create a voltage when there is a different temperature on each side.
Below sf, there are two spin carriers with opposite magnetic moments, with the carriers polarized along the field forming a majority magnon band. Spin thermoelectric effects in organic singlemolecule. Ortiz1, mohammed aldosary1, 3, cliff chen1, vivek aji1, peng wei1, and jing shi1 1. It has been shown that insulating afms are able to exhibit spin transport 14 and, moreover, thermal magnon currents induced by the spin seebeck effect sse 1511, 16, when driven into the spinflop.
The sse is usually detected by an electric voltage generated in a metallic layer in contact with the magnetic film produced by the spin to charge current conversion through the inverse spin hall effect ishe. An example of this antiferromagnetic phenomenon is mangenese ii oxide. Spinvalley filter effect and seebeck effect in a silicene. The sse is usually detected by an electric voltage generated in a. The fieldinduced spinflop sf transition of neel order is associated with a qualitative change in sse behavior. We demonstrate spin seebeck microscopy as a sensitive tabletop method for imaging antiferromagnetism in thin films and apply this technique to study spin torque switching in ptnio and ptniopt heterostructures. Conversely, when a voltage is applied to it, heat is transferred from one side to the other, creating a temperature difference. Pdf spin seebeck effect near the antiferromagnetic spin. Paramagnetic and antiferromagnetic spin seebeck effect. Since then, many new spin caloritronics devices have been theoretical designed and many physical effects have been discovered, including spin dependent seebeck diode sdsd effects, the negative differential spin seebeck effect, the spin dependent seebeck effect sdse, and the thermal colossal magnetoresistance effect. The spin seebeck effect sse consists in the generation of a spin current by a temperature gradient applied in a magnetic film. Recently, the spin seebeck effect has also been observed in magnetic tunnel. Utilization of the antiferromagnetic irmn electrode in. Arati prakash1, jack brangham1, fengyuan yang1, joseph p.
Coherent spin pumping versus incoherent spin seebeck effect. Spin seebeck effect through antiferromagnetic nio arxiv. Antiferromagnets are beneficial for future spintronic applications due to their zero magnetic moment and ultrafast dynamics. Spin thermoelectric effects in organic singlemolecule devices. Antiferromagnetic materials proved to be essential in gmr sensors for pinning the magnetization of a reference ferromagnetic layer by means of the exchange bias phenomenon. Spin transport across antiferromagnets induced by the spin. The seebeck effect converts thermal gradients into electricity. Abstract the spin seebeck effect sse consists in the generation of a spin current by a temperature gradient applied in a magnetic film. However, spin current generation via antiferromagnetic resonance and simultaneous electrical detection by the inverse spin hall effect in heavy metals have not yet been explicitly demonstrated 4,5,6. The spin seebeck effect refers to the generation of a spin voltage caused by a temperature gradient in a ferromagnet, which enables the thermal injection of spin currents from the ferromagnet into an attached nonmagnetic metal over a macroscopic scale of several millimeters. Spin transport in multilayer systems with fully epitaxial. Department of physics and astronomy, university of california, riverside, california 92521. In spintronics, the antiferromagnetic metal irmn has been used as the pinning layer in magnetic tunnel junctions that form.