Benjamin Pigeau

A frequency-controlled magnetic vortex memory

Using the ultra low damping NiMnSb half-Heusler alloy patterned into vortex-state magnetic nano-dots, we demonstrate a new concept of non-volatile memory controlled by the frequency. A perpendicular bias magnetic field is used to split the frequency of the vortex core gyrotropic rotation into two distinct frequencies, depending on the sign of the vortex core polarity

Bistability of vortex core dynamics in a single perpendicularly magnetized nanodisk.

p=\pm1

Optimal control of vortex-core polarity by resonant microwave pulses

inside the dot. A magnetic resonance force microscope and microwave pulses applied at one of these two resonant frequencies allow for local and deterministic addressing of binary information (core polarity).

Identification and selection rules of the spin-wave eigen-modes in a normally magnetized nano-pillar

Microwave spectroscopy of individual vortex-state magnetic nanodisks in a perpendicular bias magnetic field H is performed using a magnetic resonance force microscope. It reveals the splitting induced by H on the gyrotropic frequency of the vortex core rotation related to the existence of the two stable polarities of the core. This splitting enables spectroscopic detection of the core polarity. The bistability extends up to a large negative (antiparallel to the core) value of the bias magnetic field Hr, at which the core polarity is reversed. The difference between the frequencies of the two stable rotational modes corresponding to each core polarity is proportional to H and to the ratio of the disk thickness to its radius. Simple analytic theory in combination with micromagnetic simulations give a quantitative description of the observed bistable dynamics.

A universal and ultrasensitive vectorial nanomechanical sensor for imaging 2D force fields

In magnetic nanostructures, the core of a vortex points either up or down, and the polarity can be reversed by alternating-field pulses. An experiment now demonstrates deterministic and coherent control of vortex-core polarity using sequences of resonant microwave pulses and highlights routes to optimizing the technique, which might find application in magnetic-storage devices.

Measurement of the dynamical dipolar coupling in a pair of magnetic nanodisks using a ferromagnetic resonance force microscope.

We report on a spectroscopic study of the spin-wave eigen-modes inside an individual normally magnetized two layers circular nano-pillar (Permalloy

Probing the Anharmonicity of the Potential Well for a Magnetic Vortex Core in a Nanodot

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Synchronizing the dynamics of a single nitrogen vacancy spin qubit on a parametrically coupled radio-frequency field through microwave dressing.

Copper

Tuning of oxidation states in the LaNiO3−δ perovskite around the insulator-metal transition

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Observation of a phononic Mollow triplet in a multimode hybrid spin-nanomechanical system

Permalloy) by means of a Magnetic Resonance Force Microscope (MRFM). We demonstrate that the observed spin-wave spectrum critically depends on the method of excitation. While the spatially uniform radio-frequency (RF) magnetic field excites only the axially symmetric modes having azimuthal index