32 research outputs found
Effective ferromagnetic coupling between a superconductor and a ferromagnet in LaCaMnO/Nb hybrids
In this work we present magnetization data on hybrids consisting of
multilayers (MLs) of man- ganites [La0.33Ca0.67MnO3/La0.60Ca0.40MnO3]15 in
contact with a low-Tc Nb superconductor (SC). Although a pure SC should behave
diamagnetically in respect to the external magnetic field in our ML-SC hybrids
we observed that the magnetization of the SC follows that of the ML. Our
intriguing experimental results show that the SC below its TSC c becomes
ferromagnetically coupled to the ML. As a result in the regime where
diamagnetic behaviour of the SC was expected its bulk magne- tization switches
only whenever the coercive field of the ML is exceeded. By employing specific
experiments where the ML was selectively biased or not we demonstrate that the
ML inflicts its magnetic properties on the whole hybrid. Possible explanations
are discussed in connection to recent theoretical proposals and experimental
findings that were obtained in relative hybrids.Comment: To appear in Phys. Rev.
Extrinsic Magnetotransport Phenomena in Ferromagnetic Oxides
This review is focused on extrinsic magnetotransport effects in ferromagnetic
oxides. It consists of two parts; the second part is devoted to an overview of
experimental data and theoretical models for extrinsic magnetotransport
phenomena. Here a critical discussion of domain-wall scattering is given.
Results on surfacial and interfacial magnetism in oxides are presented.
Spin-polarized tunnelling in ferromagnetic junctions is reviewed and
grain-boundary magnetoresistance is interpreted within a model of
spin-polarized tunnelling through natural oxide barriers. The situation in
ferromagnetic oxides is compared with data and models for conventional
ferromagnets. The first part of the review summarizes basic material
properties, especially data on the spin-polarization and evidence for
half-metallicity. Furthermore, intrinsic conduction mechanisms are discussed.
An outlook on the further development of oxide spin-electronics concludes this
review.Comment: 133 pages, 47 figures, submitted to Rep. Prog. Phy
Magnetic properties of nanowires with ferromagnetic core and antiferromagnetic shell
We present a Monte Carlo study of the magnetic properties of thin cylindrical nanowires composed of a ferromagnetic core and an antiferromagnetic shell implementing a classical spin Hamiltonian. We address systematically the impact of interface exchange coupling on the loop characteristics and the magnetization reversal mechanism. We study the effect of shell polycrystallinity on the characteristic fields of the isothermal hysteresis loop (coercivity, exchange-bias). We demonstrate that coupling to a polycrystalline antiferromagnetic shell increases the critical core diameter for transition from transverse to vortex domain walls. © 201