Interfacial exchange coupling in Fe-Tb/[Co/Pt] heterostructures

Schubert, Christian; Hebler, Birgit; Schletter, Herbert; Liebig, Andreas; Daniel, M.; Abrudan, R.; Radu, F.; Albrecht, Manfred

doi:10.1103/physrevb.87.054415

Cited by 37 publications

(54 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…With increasing temperature, the EB shift gets slightly reduced and starts to vanish above 140 K, as indicated by the appearance of a symmetric reversal part of the hysteresis between ±15 kOe, which becomes more pronounced with increasing temperature. At 200 K and above, a fully symmetric hysteresis loop, characteristic of an antiferromagnetically coupled bilayer, as discussed before, is observed [11,14]. By cooling the system down to 80 K in a negative field of −70 kOe and measuring subsequently hysteresis loops from 80 K toward higher temperatures, the same evolution of the EB phenomenon is observed, except that the shifts are inverted [ Fig.…”

Section: Resultssupporting

confidence: 53%

“…In addition to AFM/FM interfaces, EB has also been reported in systems with ferrimagnetic (FI)/FM layers [10][11][12][13][14][15][16][17][18][19][20][21][22][23], resulting in giant EB fields in the order of several tens of kilo-Oersteds [13,14,[24][25][26]. In particular, FI layers consisting of amorphous heavy rare earth (RE)-3d transition metal (TM) alloys provide further benefits as a pinning layer since these alloys can exhibit large interfacial exchange interaction and zero moment at the compensation temperature T comp .…”

Section: Introductionmentioning

confidence: 99%

“…Considering a heterostructure, consisting of two FI layers, where one layer is RE dominated and the other is TM dominated, in the ground state, the net moments of each layer are antiparallel aligned. However, by reversing the softer layer against the hard layer, an interfacial domain wall (IDW) at the transition region between the two layers will be created [11,14]. Reducing the external field leads to annihilation of the IDW, forcing the softer layer to rotate back which results in a positive loop shift under this minor loop condition.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Double exchange bias in ferrimagnetic heterostructures

et al. 2017

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Resultssupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Double exchange bias in ferrimagnetic heterostructures

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…Examples for anomalous include the relative diffusion of tracers particles in fully turbulent [5] or weakly chaotic [6] systems as well as in groundwater aquifers [7]. Subdiffusion of charge carriers in amorphous semiconductors was originally analysed some 40 years ago [8] but is now regaining attention in the study of polymeric semiconductors [9]. However, the main current impetus for the study of anomalous diffusion processes is due to modern spectroscopic tools such as fluorescence correlation spectroscopy [10] and single particle tracking of submicron particles [11].…”

Section: Introductionmentioning

confidence: 99%

Ergodicity breaking, ageing, and confinement in generalized diffusion processes with position and time dependent diffusivity

Cherstvy

Metzler

2015

J. Stat. Mech.

View full text Add to dashboard Cite

We study generalised anomalous diffusion processes whose diffusion coefficient D(x, t) ∼ D 0 |x| α t β depends on both the position x of the test particle and the process time t. This process thus combines the features of scaled Brownian motion and heterogeneous diffusion parent processes. We compute the ensemble and time averaged mean squared displacements of this generalised diffusion process. The scaling exponent of the ensemble averaged mean squared displacement is shown to be the product of the critical exponents of the parent processes, and describes both subdiffusive and superdiffusive systems. We quantify the amplitude fluctuations of the time averaged mean squared displacement as function of the length of the time series and the lag time. In particular, we observe a weak ergodicity breaking of this generalised diffusion process: even in the long time limit the ensemble and time averaged mean squared displacements are strictly disparate. When we start to observe this process some time after its initiation we observe distinct features of ageing. We derive a universal ageing factor for the time averaged mean squared displacement containing all information on the ageing time and the measurement time. External confinement is shown to alter the magnitudes and statistics of the ensemble and time averaged mean squared displacements.

show abstract

“…Besides the classical system of AF/FM interfaces, EB and related effects have been observed also in other types of samples, e.g. involving ferrimagnets (FI): AF/FI 13 , FI/FM [14][15][16] and lately also in FI/FI 17 with a compensated spin structures at the interface. Transition Metal-Rare Earth (TM-RE) alloys, in particular, are nowadays suggested to used as FI materials in magnetic hybrid structures exhibiting strong EB effects 18 .…”

mentioning

confidence: 99%

Observation of an atomic exchange bias effect in DyCo<inf>4</inf> film

Chen

Dieter

Radu

2015

2015 IEEE Magnetics Conference (INTERMAG)

Self Cite

View full text Add to dashboard Cite

The fundamental important and technologically widely employed exchange bias effect occurs in general in bilayers of magnetic thin films consisting of antiferromagnetic and ferromagnetic layers where the hard magnetization behavior of an antiferromagnetic thin film causes a shift in the magnetization curve of a soft ferromagnetic film. The minimization of the single magnetic grain size to increase the storage density and the subsequent demand for magnetic materials with very high magnetic anisotropy requires a system with high H EB . Here we report an extremely high H EB of 4 Tesla observed in a single amorphous DyCo 4 film close to room temperature. The origin of the exchange bias can be associated with the variation of the magnetic behavior from the surface towards the bulk part of the film revealed by X-ray absorption spectroscopy and X-ray magnetic circular dichroism techniques utilizing the bulk sensitive transmission and the surface sensitive total electron yield modes. The competition between the atomic exchange coupling in the single film and the Zeeman interaction lead to an intrinsic exchanged coupled system and the so far highest exchange bias effect H EB = 4 Tesla reported in a single film, which is accommodated by a partial domain wall formation.Exchange bias effect (EB) was discovered in 1956 by Meiklejohn and Bean when studying Co particles embedded in their native antiferromagnetic oxide 1 . It is generally considered to form from an uncompensated spin configuration at the ferromagnetic/antiferromagnetic (FM/AF) interface 2,3 , as it is the case in small particles, inhomogeneous materials, FM films on AF single crystals and FM on AF thin films 4 with frozen and rotatable spins at their interfaces [5][6][7][8][9] . Phenomenologically, the EB effect in FM/AF systems displays a shift of the hysteresis by an EB field H EB that is achieved by a magnetic field cooling procedure down to the Néel temperature T N of the AF. The experimentally observed value of the H EB in FM/AF systems, however, is in general several orders of magnitude below the theoretical prediction for a perfect EB system 10 . This discrepancy resulted in a heavy debate and the development of sophisticated models for the explanation of the origin of the EB effect and its drastic reduction of the EB effect in real EB systems 4,11,12 . Besides the classical system of AF/FM interfaces, EB and related effects have been observed also in other types of samples, e.g. involving ferrimagnets (FI): AF/FI 13 , FI/FM 14-16 and lately also in FI/FI 17 with a compensated spin structures at the interface. Transition Metal-Rare Earth (TM-RE) alloys, in particular, are nowadays suggested to used as FI materials in magnetic hybrid structures exhibiting strong EB effects 18 . Besides an interfacial exchange between two chemically and magnetically different compositions, a physically induced magnetic phase deviation from the bulk to the surface may also results into an exchange bias effect although there is no obvious chemical interface in the sample. The...

show abstract

Interfacial exchange coupling in Fe-Tb/[Co/Pt] heterostructures

Cited by 37 publications

References 30 publications

Double exchange bias in ferrimagnetic heterostructures

Double exchange bias in ferrimagnetic heterostructures

Ergodicity breaking, ageing, and confinement in generalized diffusion processes with position and time dependent diffusivity

Observation of an atomic exchange bias effect in DyCo<inf>4</inf> film

Contact Info

Product

Resources

About