Concept

Superparamagnétisme

Publications associées (213)

The remarkable difference between surface and step atoms in the magnetic anisotropy of two-dimensional nanostructures

Harald Brune, Stefano Rusponi, Philipp Buluschek, Nicolas Weiss, Laurent Claude

The original magnetic properties of nanometre-sized particles are due to the distinct contributions of volume, surface and step atoms. To disentangle these contributions is an ongoing challenge of materials science. Here we introduce a method enabling the ...

2003

Giant magnetic anisotropy of single cobalt atoms and nanoparticles

Klaus Kern, Harald Brune, Stefano Rusponi, Pietro Gambardella

The isotropic magnetic moment of a free atom is shown to develop giant magnetic anisotropy energy due to symmetry reduction at an atomically ordered surface. Single cobalt atoms deposited onto platinum ( 111) are found to have a magnetic anisotropy energy ...

2003

Sawtoothlike de Haas–van Alphen oscillations of a two-dimensional electron system

Dirk Grundler

We present studies on the low-temperature magnetization of a two-dimensional electron system (2DES) in the integer quantum Hall-effect regime. The 2DES was formed in a modulation-doped AlGaAs/GaAs heterojunction. Using molecular-beam epitaxy it has been in ...

2002

Magnetic interactions and electronic states in superconducting and nonsuperconducting ruthenocuprates

Giorgio Margaritondo, Ivica Zivkovic, Luca Perfetti

We measured polycrystalline samples of SrRuO3 and both superconducting and nonsuperconducting (hydrogen loaded) ruthenocuprates-Eu1.5Ce0.5RuSr2Cu2O10-x (Ru-1222)-samples using ac susceptibility, Ru 3p x-ray photoemission and Ru 2p x-ray-absorption measurem ...

2002

Superconducting transition in ruthenocuprate RuSr2GdCu2O8 viewed from the studies of the imaginary part of ac susceptibility

Davor Pavuna, Ivica Zivkovic, Helmuth Berger

We have measured two structurally similar superconducting systems, RuSr2GdCu2O8 and GdBa2Cu3O7 by means of high-resolution ac susceptibility. The real and the imaginary part of ac susceptibility of both bulk-ceramic and powdered samples have been studied d ...

2002

Light controlled and probed ferromagnetism of (Cd,Mn)Te quantum wells

Benoît Marie Joseph Deveaud

Properties of carrier-induced ferromagnetism in modulation-doped quantum wells of p-type (Cd,Mn)Te are assessed by photoluminescence (PL) and PL excitation spectroscopy. Well-chosen illumination makes it possible to deplete the quantum well and thus to con ...

2002

Magnetization of semiconductor quantum dots

Dirk Grundler

We present experimental studies of the magnetization of electrons in semiconductorquantum dots. Starting from a modulation-doped AlGaAs/GaAs heterostructure an array of dots was patterned by laser-interference lithography and deep mesa etching. The quantum ...

American Institute of Physics2002

Electronic and magnetic properties of ruthenocuprates

Giorgio Margaritondo, Sylvain Roy, Luca Perfetti

We report on X-ray photoemission of core levels, valence band studies using angle-integrated photoemission, and magnetization measurements of ruthenocuprate and SrRuO3 polycrystalline samples. The data indicate that the RuO2 planes are the source of the en ...

2001

Finite element method simulation of ac loss in HTS tapes with B-dependent E-J power law

Bertrand Dutoit

The nonlinear behavior of High Temperature Superconductors (HTS) is often modeled by an E-J power law in order to describe their electromagnetic properties. This paper presents AC loss calculations in HTS tapes, performed by means of FEM commercial softwar ...

2001

Effect of tilted magnetic fields on bistable nanomagnets in hybrid semiconductor/ferromagnet devices

Dirk Grundler

Using the anisotropic Hall effect in a sub-micron lithographically well-defined two-dimensional electron system we measure the stray field of individual ferromagnetic nanoparticles in tilted magnetic fields. Our model calculations and experimental data sho ...

Elsevier2000

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