Zero Helicity States in the LaAlO3-SrTiO3 Interface

Rodrigues, Edinardo I. B.; Vargas-Paredes, Alfredo A.; Doria, Mauro M.; Cariglia, Marco

doi:10.1007/s10948-016-3675-z

Cited by 7 publications

(6 citation statements)

References 34 publications

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“…We would have expected that the samples showing a sizable torque signal would also provide a measurable magnetic signal in the scanning SQUID (see also Ref. [29] for a discussion of the origin of the torque signals). Comparing the limits established by S-SQUID to moment densities measured by bulk probes requires assumptions about the moment distribution and density in either experiment.…”

Section: Discussionmentioning

confidence: 99%

“…Early density function theory (DFT) calculations of the electronic properties of the ntype LaAlO 3 /SrTiO 3 interface indicated moments induced by spin-selective filling of orbitals [26], geometrical confinement [27], or band narrowing caused by lattice modifications [28]. Kinetically driven mechanisms [29] and interactions between localized and mobile charge carriers [30][31][32][33] may also intrinsically generate net magnetic moments at the interface. In addition to these intrinsic mechanisms, defects have been identified that could cause the interface to be magnetic.…”

Section: Introductionmentioning

confidence: 99%

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Exploring possible ferromagnetism of the LaAlO3/SrTiO3 interface

Wittlich

Boschker

Asaba

et al. 2019

Phys. Rev. Materials

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We report on extensive investigations of magnetism at the n-type LaAlO 3 /SrTiO 3 interface performed by utilizing a spectrum of local and integrative analytical techniques: Scanning superconducting quantum interference device microscopy, polar Kerr magnetometry, ferromagnetic resonance, and magnetic torque magnetometry. The samples originated from the same wafers. For nominally fully oxidized samples, we find that the mere presence of the conducting interface does not induce magnetism to values exceeding already present magnetic signals originating from the substrates, irrespective of the measurement technique. With the controlled introduction of oxygen vacancies, however, the different analytical techniques with their inherently different sensitivities and potential interactions with possible magnetic moments in the samples yield different results concerning the existence of magnetism. These unexpected differences obtained with the various measurement techniques are a possible source of the disagreement in the literature about the existence of ferromagnetism at LaAlO 3 /SrTiO 3 interfaces.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Exploring possible ferromagnetism of the LaAlO3/SrTiO3 interface

Wittlich

Boschker

Asaba

et al. 2019

Phys. Rev. Materials

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“…The functions η0 and η∞, defined by Eqs. (56) and (57), respectively, are good approximations for ηT , below and above the crossover that takes place in the vicinity of µβ ∼ 1.5.…”

Section: E the Conductivities And The Number Of Particles In The Linmentioning

confidence: 91%

“…Thus the state has a lower symmetry than the theory itself, a situation commonly seen in physics in the context of the Goldstone theorem 52 . The three term decomposition of the kinetic energy is general and can be applied in other situations such as in the Ginzburg-Landau approach to layered superconductors [53][54][55][56][57] where the pseudogap can be interpreted as a topological state 58 .…”

Section: The Weyl State and The Breaking Of The Space-time Symmetriesmentioning

confidence: 99%

The linear Dirac spectrum and the Weyl states in the Drude-Sommerfeld topological model

Doria

2019

Eur. Phys. J. B

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A Drude-Sommerfeld topological model (DSTM) is proposed to describe Weyl fermions under residual collisions. They are nearly free and dressed by their own weak magnetic field that breaks the reflection and time symmetries around a layer. This weak magnetic field brings topological stability to the states through a non-trivial Chern-Simons number which is here calculated in the limit of a Dirac linear spectrum. The Weyl fermions display an energy gap and much above this gap the spectrum becomes Dirac linear. They are obtained from a Schroedinger like hamiltonian for particles with spin and magnetic energy which are momentum confined to a layer 1 . The electrical and the thermal conductivities of the Weyl fermions as well as the corresponding Wiedemman-Franz law are derived in the framework of a constant relaxation time. The Lorenz number coefficient acquires asymptotic value 6.5552 times the bulk value of π 2 /3. The relaxation time is shown to be renormalized by the inverse of the square of the gap, and so, leads to a ballistic regime in the linear Dirac spectrum limit.

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“…It can be shown that the last term of Eq. ( 6) is proportional to H 3 21 , and so, it does not contribute to the torque under assumption (ii). A way to see this proportionality is to consider that this last term vanishes for a spatially homogeneous state, namely Ψ † Ψ constant, and this is only achieved for H 3 = 0.…”

mentioning

confidence: 99%