Kondo Effect in Magnetic Tunnel Junctions

Lee, K. I.; Joo, Sung-Kwan; Lee, J. H.; Rhie, K.; Kim, Tae Suk; Lee, W. Y.; Shin, Kyung-Ho; Lee, B. C.; LeClair, P.; Lee, J. S.; Park, J. H.

doi:10.1103/physrevlett.98.107202

Cited by 31 publications

(50 citation statements)

References 36 publications

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“…7 and Supplementary Note 7). Although such physics has not been previously discussed in NLSVs, the reciprocal role of spin injection on the Kondo effect in charge transport has been explored 48 , and some precedent for related effects exists in magnetic tunnel junctions 50 . Critically, we believe that this picture provides qualitative explanations for all observed phenomena.…”

Section: Resultsmentioning

confidence: 99%

“…Such a logarithmic form around T K , with expected negative and positive deviations below and above T K , respectively, is a commonly used phenomenological description of Kondo physics 44,50 , and can be rationalized from equation (1) assuming da p [1-A log(T/T K )], that is, a Kondo-related suppression of a. An understanding beyond simple phenomenology will require an approach sophisticated enough to capture the T-dependent influence of local moments and their associated conduction electron screening, as was achieved in the normal Kondo effect via higher-order perturbation theory.…”

Section: Cumentioning

confidence: 99%

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Kondo physics in non-local metallic spin transport devices

et al. 2014

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The non-local spin-valve is pivotal in spintronics, enabling separation of charge and spin currents, disruptive potential applications and the study of pressing problems in the physics of spin injection and relaxation. Primary among these problems is the perplexing nonmonotonicity in the temperature-dependent spin accumulation in non-local ferromagnetic/ non-magnetic metal structures, where the spin signal decreases at low temperatures. Here we show that this effect is strongly correlated with the ability of the ferromagnetic to form dilute local magnetic moments in the NM. This we achieve by studying a significantly expanded range of ferromagnetic/non-magnetic combinations. We argue that local moments, formed by ferromagnetic/non-magnetic interdiffusion, suppress the injected spin polarization and diffusion length via a manifestation of the Kondo effect, thus explaining all observations. We further show that this suppression can be completely quenched, even at interfaces that are highly susceptible to the effect, by insertion of a thin non-moment-supporting interlayer.

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Section: Resultsmentioning

confidence: 99%

Section: Cumentioning

confidence: 99%

Kondo physics in non-local metallic spin transport devices

et al. 2014

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“…At low-energy the system is governed by Kondo physics, Eq. (53), [48][49][50][51] where the L-R degree of freedom plays the role of a pseudo-spin. The equivalence to Kondo continues to hold even in the presence of a charge sensor, as shown by GBG.…”

Section: Discussionmentioning

confidence: 99%

“…This behaviour can be understood as follows. 17,18,[48][49][50][51] In the vicinity of the particle-hole symmetric point, only two local charge configurations are relevant, namely those with occupancies (n L , n R ) equal to (0, 1) or (1, 0). The spin-asymmetric SIAM can thus be mapped onto an anisotropic Kondo model by a SchriefferWolff transformation.…”

Section: A Width Of Switching Regimementioning

confidence: 99%

“…17,18,[48][49][50][51] The corresponding Kondo temperature, T K , sets the width of the population switch as function of gate voltage. We calculate the spectral function A eq Y (ω) of the pseudospinflip operator and show that T K also acts as the crossover scale ω * that separates a low-frequency regime showing Fermi-liquid power laws from an intermediate-frequency regime revealing AO exponents.…”

Section: Population Switching Without Sensormentioning

confidence: 99%

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Anderson orthogonality in the dynamics after a local quantum quench

et al. 2012

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We present a systematic study of the role of Anderson orthogonality for the dynamics after a quantum quench in quantum impurity models, using the numerical renormalization group. As shown by Anderson in 1967, the scattering phase shifts of the single-particle wave functions constituting the Fermi sea have to adjust in response to the sudden change in the local parameters of the Hamiltonian, causing the initial and final ground states to be orthogonal. This so-called Anderson orthogonality catastrophe also influences dynamical properties, such as spectral functions. Their low-frequency behaviour shows non-trivial power laws, with exponents that can be understood using a generalization of simple arguments introduced by Hopfield and others for the X-ray edge singularity problem. The goal of this work is to formulate these generalized rules, as well as to numerically illustrate them for quantum quenches in impurity models involving local interactions. As a simple yet instructive example, we use the interacting resonant level model as testing ground for our generalized Hopfield rule. We then analyse a model exhibiting population switching between two dot levels as a function of gate voltage, probed by a local Coulomb interaction with an additional lead serving as charge sensor. We confirm a recent prediction that charge sensing can induce a quantum phase transition for this system, causing the population switch to become abrupt. We elucidate the role of Anderson orthogonality for this effect by explicitly calculating the relevant orthogonality exponents.

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Strongly Bias‐Dependent Tunnel Magnetoresistance in Manganite Spin Filter Tunnel Junctions

et al. 2015

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A highly unconventional bias-dependent tunnel magnetoresistance (TMR) response is observed in Sm0.75 Sr0.25 MnO3 -based nanopillar spin filter tunnel junctions (SFTJs) with two different behaviors in two different thickness regimes of the barrier layer. Thinner barrier devices exhibit conventional SFTJ behaviors; however, for larger barrier thicknesses, the TMR-bias dependence is more complex and reverses sign at higher bias.

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Kondo Effect in Magnetic Tunnel Junctions

Cited by 31 publications

References 36 publications

Kondo physics in non-local metallic spin transport devices

Kondo physics in non-local metallic spin transport devices

Anderson orthogonality in the dynamics after a local quantum quench

Strongly Bias‐Dependent Tunnel Magnetoresistance in Manganite Spin Filter Tunnel Junctions

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