Electrical switching of an antiferromagnet

Wadley, P.; Howells, B.; Železný, Jakub; Andrews, C.; Hills, V.; Campion, R. P.; Novák, V.; Olejník, K.; Maccherozzi, F.; Dhesi, S. S.; Martín, Sergi; Wagner, Thomas; Wunderlich, J.; Freimuth, Frank; Mokrousov, Yuriy; Kuneš, J.; Chauhan, Jasbinder; Grzybowski, M. J.; Rushforth, A. W.; Edmonds, K. W.; Gallagher, B. L.; Jungwirth, T.

doi:10.1126/science.aab1031

Cited by 1,234 publications

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“…Wadley et al [13] showed that in AFMs with a specific crystal and magnetic structures, AFM moments can be manipulated electrically. Several studies have also focused on transmission and detection of spin-currents in AFMs.…”

Section: Introductionmentioning

confidence: 99%

Electrical manipulation of ferromagnetic NiFe by antiferromagnetic IrMn

et al. 2015

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We demonstrate that an antiferromagnet can be employed for a highly efficient electrical manipulation of a ferromagnet. In our study, we use an electrical detection technique of the ferromagnetic resonance driven by an in-plane ac current in a NiFe/IrMn bilayer. At room temperature, we observe antidampinglike spin torque acting on the NiFe ferromagnet, generated by an in-plane current driven through the IrMn antiferromagnet. A large enhancement of the torque, characterized by an effective spin-Hall angle exceeding most heavy transition metals, correlates with the presence of the exchange-bias field at the NiFe/IrMn interface. It highlights that, in addition to the strong spin-orbit coupling, the antiferromagnetic order in IrMn governs the observed phenomenon.

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Section: Introductionmentioning

confidence: 99%

Electrical manipulation of ferromagnetic NiFe by antiferromagnetic IrMn

et al. 2015

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“…There are no stray fields in antiferromagnets, making them more robust against the influence of external magnetic fields. The recent discovery of anisotropic magnetoresistance [15][16][17], spin-orbit torques [18], and electrical switching of an antiferromagnet [19] demonstrate the feasibility of antiferromagnets as active spintronics components.The real benefit of antiferromagnets is that they can enable terahertz circuits. Unlike ferromagnets, the resonance frequency of antiferromagnets is also governed by the tremendous exchange energy.…”

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confidence: 99%

Spin pumping and inverse spin Hall voltages from dynamical antiferromagnets

Johansen

Brataas

2017

Phys. Rev. B

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Dynamical antiferromagnets can pump spins into adjacent conductors. The high antiferromagnetic resonance frequencies represent a challenge for experimental detection, but magnetic fields can reduce these resonance frequencies. We compute the ac and dc inverse spin Hall voltages resulting from dynamical spin excitations as a function of a magnetic field along the easy axis and the polarization of the driving ac magnetic field perpendicular to the easy axis. We consider the insulating antiferromagnets MnF 2 , FeF 2 , and NiO. Near the spin-flop transition, there is a significant enhancement of the dc spin pumping and inverse spin Hall voltage for the uniaxial antiferromagnets MnF 2 and FeF 2 . In the uniaxial antiferromagnets it is also found that the ac spin pumping is independent of the external magnetic field when the driving field has the optimal circular polarization. In the biaxial NiO, the voltages are much weaker, and there is no spin-flop enhancement of the dc component. DOI: 10.1103/PhysRevB.95.220408 Spin pumping is a versatile tool for probing spin dynamics in ferromagnets [1][2][3][4][5][6]. The magnitude of the pumped spin currents reveals information about the magnetization dynamics and the electron-magnon coupling at interfaces [7][8][9]. The precessing spins generate a pure spin flow into adjacent conductors. Inside the conductor, the resulting spin accumulation and currents give insight into the spin-orbit coupling. The inverse spin Hall effect (ISHE) is often used to convert the pure spin current into a charge current, which is detected [10,11]. Additionally, the induced nonequilibrium spins can be probed with x-ray magnetic circular dichroism measurements [12,13].Antiferromagnets differ strikingly from ferromagnets [14]. There are no stray fields in antiferromagnets, making them more robust against the influence of external magnetic fields. The recent discovery of anisotropic magnetoresistance [15][16][17], spin-orbit torques [18], and electrical switching of an antiferromagnet [19] demonstrate the feasibility of antiferromagnets as active spintronics components.The real benefit of antiferromagnets is that they can enable terahertz circuits. Unlike ferromagnets, the resonance frequency of antiferromagnets is also governed by the tremendous exchange energy. We recently demonstrated that the transverse spin conductance, a governing factor of spin pumping, is as large in antiferromagnet-normal metal junctions (AF|N) as in ferromagnet-normal metal junctions [20]. Furthermore, this result is valid even when the magnetic system is insulating. The firm electron-magnon coupling at the interface opens the door for electrical probing of the ultrafast spin dynamics in antiferromagnets [20,21].Precessing spins in antiferromagnets generate terahertz currents in adjacent conductors. This ability opens new territory in high-frequency spintronics. Such studies could become influential in gathering vital insight into fast electron dynamics and eventually for a broad range of applications. These electric sign...

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“…As originally realized by Dresselhaus 1 and Rashba 2 , SO coupling in a noncentrosymmetric crystal lifts the degeneracy of the Bloch states at a given k-point and locks their momenta and spin polarizations together giving rise to a spin texture in reciprocal space. This leads to a number of phenomena 3 such as spin-torques in ferro- 4,5 and anti-ferromagnets 6,7 , topological states of matter, or spin textures in the reciprocal space that are the basis of the spin galvanic effect. 8 Electronic correlations alone can provide coupling between spin polarization and charge currents, e.g., via effective magnetic fields acting on electrons moving through a non-coplanar spin background.…”

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Spontaneous Spin Textures in Multiorbital Mott Systems

Kuneš

Geffroy

2016

Phys. Rev. Lett.

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Spin textures in k-space arising from spin-orbit coupling in non-centrosymmetric crystals find numerous applications in spintronics. We present a mechanism that leads to appearance of kspace spin texture due to spontaneous symmetry breaking driven by electronic correlations. Using dynamical mean-field theory we show that doping a spin-triplet excitonic insulator provides a means of creating new thermodynamic phases with unique properties. The numerical results are interpreted using analytic calculations within a generalized double-exchange framework.PACS numbers: 71.70. Ej,71.27.+a,75.40.Gb Manipulation of spin polarization by controlling charge currents and vice versa has attracted considerable attention due to applications in spintronic devices. A major role is played by spin-orbit (SO) coupling in non-centrosymmetric systems. As originally realized by Dresselhaus 1 and Rashba 2 , SO coupling in a noncentrosymmetric crystal lifts the degeneracy of the Bloch states at a given k-point and locks their momenta and spin polarizations together giving rise to a spin texture in reciprocal space. This leads to a number of phenomena 3 such as spin-torques in ferro-4,5 and anti-ferromagnets 6,7 , topological states of matter, or spin textures in the reciprocal space that are the basis of the spin galvanic effect. 8 Electronic correlations alone can provide coupling between spin polarization and charge currents, e.g., via effective magnetic fields acting on electrons moving through a non-coplanar spin background. 9,10 Wu and Zhang 11 proposed that SO coupling can be generated dynamically in analogy to the breaking of relative spin-orbit symmetry in 3 He 12 . Subsequently, an effective field theory of spin-triplet Fermi surface instabilities with high orbital partial wave was developed in Ref. 13.Here, we present a spontaneous formation of a k-space spin texture, similar to the effect of Rashba-Dresselhaus SO coupling, in centrosymmetric bulk systems with no intrinsic SO coupling. The spin texture is a manifestation of excitonic magnetism that has been proposed to take place in some strongly correlated materials. 14,15 The basic ingredient is a crystal built of atoms with quasidegenerate singlet/triplet ground states. Under suitable conditions a spin-triplet exciton condensate 16,17 is formed, which may adopt a variety of thermodynamic phases with diverse properties 18 . Several experimental realizations of excitonic magnetism have already been discussed in the literature. [19][20][21][22][23] Model. We use the dynamical mean-field theory (DMFT) to study the minimal model of an excitonic magnet -the two-orbital Hubbard Hamiltonian at half- fillingThe local part of the Hamiltonian contains the crystalfield splitting ∆ between the orbitals labeled a and b and the Coulomb interaction with ferromagnetic Hund's exchange J. The kinetic part H t describes the nearestneighbor hopping on the square lattice between the same orbital flavors t a , t b as well as cross-hopping between the different orbital flavors V 1 , V 2 , see Fi...

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Electrical switching of an antiferromagnet

Cited by 1,234 publications

References 37 publications

Electrical manipulation of ferromagnetic NiFe by antiferromagnetic IrMn

Electrical manipulation of ferromagnetic NiFe by antiferromagnetic IrMn

Spin pumping and inverse spin Hall voltages from dynamical antiferromagnets

Spontaneous Spin Textures in Multiorbital Mott Systems

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