All-optical helicity dependent magnetic switching in an artificial zero moment magnet

Schubert, Christian; Hassdenteufel, Alexander; Matthes, Patrick; Schmidt, Johannes; Helm, M.; Bratschitsch, Rudolf; Albrecht, Manfred

doi:10.1063/1.4866803

Cited by 55 publications

(49 citation statements)

References 35 publications

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“…Recently, all-optical switching (AOS) using ultrafast laser has been discovered in a-TbFeCo thin films. 5,43 Our findings also imply that the biased a-TbFeCo thin film may be potential for the new AOS devices.…”

Section: Main Contentmentioning

confidence: 59%

“…1,2 Recently the EB effect has received intensive study because of its importance in a variety of technological applications, especially in spin-valve devices and magnetic tunnel junctions. [3][4][5][6][7][8][9] The exchange anisotropy has been interpreted in terms of the exchange interaction across the ferromagnetic (FM)-antiferromagnetic (AFM) interface, e.g. in Co/IrMn.…”

Section: Main Contentmentioning

confidence: 99%

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Exchange bias and bistable magneto-resistance states in amorphous TbFeCo thin films

Chung

et al. 2016

Applied Physics Letters

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Abstract:Amorphous TbFeCo thin films sputter deposited at room temperature on thermally oxidized Si substrate are found to exhibit strong perpendicular magnetic anisotropy (PMA). Atom probe tomography (APT), scanning transmission electron microscopy (STEM), and energy dispersive spectroscopy (EDS) mapping have revealed two nanoscale amorphous phases with different Tb atomic percentages distributed within the amorphous film. Exchange bias accompanied by bistable magneto-resistance states has been uncovered near room temperature by magnetization and magneto-transport measurements. The exchange anisotropy originates from the exchange interaction between the ferrimagnetic and ferromagnetic components corresponding to the two amorphous phases. This study provides a platform for exchange bias and magneto-resistance switching using single-layer amorphous ferrimagnetic thin films that require no epitaxial growth. a

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Section: Main Contentmentioning

confidence: 59%

Section: Main Contentmentioning

confidence: 99%

Exchange bias and bistable magneto-resistance states in amorphous TbFeCo thin films

Chung

et al. 2016

Applied Physics Letters

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“…1(a). As expected, both layers do not show a compensation temperature for these compositions and stay either Tb or Fe dominant [32,33]. We also determined the uniaxial magnetic anisotropy constant K U of both layers as a function of temperature using the expression…”

Section: Resultsmentioning

confidence: 99%

Double exchange bias in ferrimagnetic heterostructures

et al. 2017

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We report on the magnetic reversal characteristics of exchange coupled ferrimagnetic (FI) Tb 19 Fe 81 /Tb 36 Fe 64 heterostructures. Both layers are amorphous and exhibit strong perpendicular magnetic anisotropy. The investigated heterostructures consist of a Tb-dominated and a Fe-dominated FI layer. Thus, in the magnetic ground state the net moments of the individual layers are oppositely aligned due to antiferromagnetic coupling of Fe and Tb moments. By cooling the system below 160 K, a large positive and negative exchange bias (EB) effect appears for the Tb-and Fe-dominated layers, respectively. The biasing depends only on the initial magnetization state and is neither affected by a cooling field nor by loop cycling. The phenomenon can be explained by the presence of a hard magnetic Fe-dominated interfacial layer, which forms during the sputter deposition process due to interface mixing and resputtering effects. This interfacial layer acts as a pinning layer below a certain temperature, where its coercivity increases to values larger than the accessible magnetic field range. This assumption is further supported by introducing a 0.9-nm-thick Ru spacer layer, which causes the EB effect to vanish. The EB effect was further investigated for a sample series, where the thickness ratio of the two Tb-Fe layers was varied, while keeping the total thickness of the bilayers constant. Only samples where the individual layers are sufficiently thick reveal double shifted loops, indicating the high sensitivity of the observed bias effect with respect to the magnetic properties of the individual layers and their interfacial area.

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“…All-optical helicity-related switching has been demonstrated in a variety of metallic materials, as e.g., rareearth transition-metal ferrimagnets, synthetic antiferromagnets, and ferromagnets [2,[6][7][8]21]. To investigate the influence of the magnetic structure on the IFE response we have computed the K IFE of synthetic antiferromagnetic Fe.…”

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confidence: 99%

Ab InitioTheory of Coherent Laser-Induced Magnetization in Metals

et al. 2016

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We present the first materials specific ab initio theory of the magnetization induced by circularly polarized laser light in metals. Our calculations are based on non-linear density matrix theory and include the effect of absorption. We show that the induced magnetization, commonly referred to as inverse Faraday effect, is strongly materials and frequency dependent, and demonstrate the existence of both spin and orbital induced magnetizations which exhibit a surprisingly different behavior. We show that for nonmagnetic metals (as Cu, Au, Pd, Pt) and antiferromagnetic metals the induced magnetization is antisymmetric in the light's helicity, whereas for ferromagnetic metals (Fe, Co, Ni, FePt) the imparted magnetization is only asymmetric in the helicity. We compute effective optomagnetic fields that correspond to the induced magnetizations and provide guidelines for achieving all-optical helicity-dependent switching.PACS numbers: 78.20. Ls, 75.70.Tj, 75.60.Jk All-optical helicity-dependent magnetization switching has recently emerged as a promising way to manipulate and ultimately control the magnetization in a magnetic material using ultrashort optical laser pulses [1][2][3][4][5][6][7]. As femtosecond optical laser pulses are the shortest stimuli known to mankind, all-optical helicity-dependent switching offers novel options to achieve magnetization reversal at a hitherto unprecedented speed. The action of a circularly polarized laser pulse on the magnetization of a material was at first observed for an antiferromagnetic 3d-metal oxide [1] and later magnetization reversal was demonstrated in a ferrimagnetic rare-earth transitionmetal alloy [2,8]. Importantly, recent work demonstrated that all-optical helicity-dependent switching is not limited to a special class of materials, but can be achieved in a broader variety of material classes, including metallic multilayers, synthetic ferrimagnets [6], and even ferromagnets such as FePt [7], which is the prime candidate material for future ultradense magnetic recording [9].While these discoveries exemplify that ultrafast magnetization reversal driven by circularly polarized laser pulses could soon revolutionize magnetic recording its underlying physical mechanism is poorly understood. The influence of the circularly polarized laser pulse has been attributed to the inverse Faraday effect (IFE) [1][2][3]7], which was discovered fifty years ago [10]. The IFE is an optomagnetic counterpart of the magneto-optical Faraday effect, that is, the circularly polarized laser light imparts a magnetization in the material which exerts a torque on the pre-existing magnetization and assists the magnetization switching. However, although various models for the IFE have been proposed [11][12][13][14][15][16][17] there does as yet not exist any knowledge as to how the induced magnetization, or optomagnetic field arises, and even less is known about the materials dependence of the IFE. As materials specific theory is lacking it is neither known for which materials large effects are pr...

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All-optical helicity dependent magnetic switching in an artificial zero moment magnet

Cited by 55 publications

References 35 publications

Exchange bias and bistable magneto-resistance states in amorphous TbFeCo thin films

Exchange bias and bistable magneto-resistance states in amorphous TbFeCo thin films

Double exchange bias in ferrimagnetic heterostructures

Ab InitioTheory of Coherent Laser-Induced Magnetization in Metals

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