A. L. Kobrinskii

Oscillatory Exchange Coupling and Positive Magnetoresistance in Epitaxial Oxide Heterostructures

Oscillation in the exchange coupling between ferromagnetic La(2/3)Ba(1/3)MnO3 layers with paramagnetic LaNiO3 spacer layer thickness has been observed in epitaxial heterostructures of the two oxides. This behavior is explained within the RKKY model employing an ab initio calculated band structure of LaNiO3, taking into account strong electron scattering in the spacer. Antiferromagnetically coupled superlattices exhibit a positive current-in-plane magnetoresistance.

Electronically driven superconductor-insulator transition in electrostatically doped La2CuO4+δ thin films

Using an electronic double layer transistor we have systematically studied the superconductor-to-insulator transition in La

Low-temperature glassy response of ultrathin La0.8Ca0.2MnO3 films to electric and magnetic fields

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Temperature dependence of exchange bias in La1/3Ca2/3MnO3/La2/3Ca1/3MnO3 epitaxial multilayers

CuO

Low‐Temperature Response of Ultrathin Manganite Films in a Field‐Effect Geometry

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Ambipolar gate effect and low temperature magnetoresistance of ultrathin La0.8Ca0.2MnO3 films.

thin films grown by ozone-assisted molecular-beam epitaxy. We have confirmed the high crystalline quality of the cuprate films and have demonstrated the suitability of the electronic double layer technique to continuously vary the charge density in a system that is otherwise characterized by the presence of miscibility gaps. The transport and magnetotransport results highlight the role of electron-electron interactions in the mechanism of the transition due to the proximity of the Mott-insulating state.

Electrostatic doping of high T

The glassy response of thin films of La0.8Ca0.2MnO3 to external magnetic and gated electrostatic fields in a field-effect geometry has been studied at low temperatures. A hierarchical response with irreversible memory effects, non-ergodic time evolution, aging and annealing behavior of the resistance suggest that the dynamics are governed by strain relaxation for both electronic and magnetic perturbations. Cross-coupling of charge, spin, and strain have been exploited to tune the coercivity of an ultrathin manganite film by electrostatic gating.

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A unidirectional magnetotransport anisotropy observed in thin films of exchange-biased ferromagnetic manganites is used to measure temperature dependence of exchange bias in these structures. Values of both the exchange field and the blocking temperature obtained from magnetotransport measurements significantly exceed those obtained from the hysteresis loop shift.

superconductors

Manganites, with their strong cross‐couplings between spin, charge, orbital, and lattice degrees of freedom, possess rich phase diagrams as a function of chemical doping. Under certain circumstances, manganites at a particular doping will have an admixture of phases of very different electronic, magnetic, and structural properties, but with nearly equal free energies. The properties of these systems are susceptible to external perturbations that lead phase conversion within the admixture. We have investigated the low‐temperature response of ultrathin La0.8Ca0.2MnO3 films in a field‐effect geometry to magnetic and gate electric fields. The composition is close to the phase boundary between a ferromagnetic metal at higher Ca doping and a ferromagnetic charge ordered insulator at lower Ca doping. An applied gate voltage produces a large ambipolar decrease in resistance at low temperatures, and the magnetization responds to the application of a gate voltage. The films also exhibit a hierarchical and glass‐lik...