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We conducted a thorough experimental and numerical study of the micromagnetic properties of Permalloy (Ni$_{80}$Fe$_{20}$) microdisks exhibiting target domain structures at remanence. Vortex configurations are quite common in such…

Materials Science · Physics 2021-07-07 Svetlana Ponomareva , Robert Morel , Hélène Joisten , Philippe Sabon , Bernard Dieny

We present a novel method that combines spin resonance spectroscopy with transmission electron microscopy (TEM), enabling localized in-situ detection of microwave (MW)-driven spin excitations. Our approach utilizes continuous wave MW…

The magnetization in a magnetic microdot made from soft magnetic materials can have a vortex-like ground state structure resulting from competition between the exchange and dipolar interactions. Normal mode magnon frequencies for such dots…

Materials Science · Physics 2009-11-07 B. A. Ivanov , C. E. Zaspel

We express dynamics of domain walls in ferromagnetic nanowires in terms of collective coordinates generalizing Thiele's steady-state results. For weak external perturbations the dynamics is dominated by a few soft modes. The general…

Materials Science · Physics 2008-03-31 O. A. Tretiakov , D. Clarke , Gia-Wei Chern , Ya. B. Bazaliy , O. Tchernyshyov

The vortex state, characterized by an in-plane closed flux domain structure and an out-of-plane magnetization at its centre (the vortex core), is one of the magnetic equilibria of thin soft ferromagnetic micron-size dots. In the last two…

Mesoscale and Nanoscale Physics · Physics 2015-06-03 Ricardo Zarzuela , Saül Vélez , Joan Manel Hernandez , Javier Tejada , Valentyn Novosad

Spin waves are collective excitations of magnetic systems. An attractive setting for studying long-lived spin-wave physics is the quantum Hall (QH) ferromagnet, which forms spontaneously in clean two-dimensional electron systems at low…

Mesoscale and Nanoscale Physics · Physics 2018-11-06 Di. S. Wei , Toeno van der Sar , Seung Hwan Lee , Kenji Watanabe , Takashi Taniguchi , Bertrand I. Halperin , Amir Yacoby

We study intersubband spin density collective modes in double-layer quantum Hall systems at $\nu=2$ within the time-dependent Hartree-Fock approximation. We find that these intersubband spin density excitations may soften under…

Mesoscale and Nanoscale Physics · Physics 2009-10-28 Lian Zheng , R. J. Radtke , S. Das Sarma

We report on the direct observation of spin wave and elastic wave emission from magnetic domain walls in ferromagnetic thin films. Driven by alternating homogeneous magnetic fields the magnetic domain walls act as coherent magnetisation…

Materials Science · Physics 2018-06-08 Rasmus B. Holländer , Cai Müller , Jeffrey McCord

Excitation of coherent high-frequency magnons (quanta of spin waves) is critical to the development of high-speed magnonic devices. Here we computationally demonstrate the excitation of coherent sub-terahertz (THz) magnons in ferromagnetic…

Applied Physics · Physics 2022-06-22 Shihao Zhuang , Jia-Mian Hu

We investigate the influence of periodic surface roughness in thin ferromagnetic films on shape anisotropy and magnetization behavior inside the ferromagnet. Starting from the full micromagnetic energy and using methods of homogenization…

Mathematical Physics · Physics 2017-11-22 Massimiliano Morini , Valeriy Slastikov

Magnetic excitations and spin correlations near the interface of two spin-$\frac12$ Heisenberg antiferromagnets are considered using the spin-wave approximation. When the interaction between boundary spins differs essentially from exchange…

Strongly Correlated Electrons · Physics 2019-05-21 N. Voropajeva , A. Sherman

We demonstrate the structural imaging of magnetostatic spin-wave modes hosted in a millimeter-sized ferromagnetic sphere. Unlike for low-dimensional magnetic materials, there is no prior technique to image these modes in bulk magnetized…

Materials Science · Physics 2019-08-07 Arnaud Gloppe , Ryusuke Hisatomi , Yosuke Nakata , Yasunobu Nakamura , Koji Usami

The entropy stabilized oxide Mg$_{0.2}$Co$_{0.2}$Ni$_{0.2}$Cu$_{0.2}$Zn$_{0.2}$O exhibits antiferromagnetic order and magnetic excitations, as revealed by recent neutron scattering experiments. This observation raises the question of the…

Disordered Systems and Neural Networks · Physics 2021-09-29 Tom Berlijn , Gonzalo Alvarez , David S. Parker , Raphaël P. Hermann , Randy S. Fishman

We have studied ferromagnetic Permalloy clusters obtained by electrodeposition on n-type silicon. Magnetization measurements reveal hysteresis loops almost independent on temperature and very similar in shape to those obtained in nanodisks…

We theoretically study spin-wave modes and their intense excitations activated by microwave magnetic fields in the skyrmion-crystal phase of insulating magnets by numerically analyzing a two-dimensional spin model using the…

Strongly Correlated Electrons · Physics 2012-01-09 Masahito Mochizuki

Spin-torque oscillators are strong candidates as nano-scale microwave generators and detectors. However, because of large amplitude-phase coupling (non-linearity), phase noise is enhanced over other linear auto-oscillators. One way to…

Mesoscale and Nanoscale Physics · Physics 2017-04-05 Muftah Al-Mahdawi , Yusuke Toda , Yohei Shiokawa , Masashi Sahashi

Nearest-neighbor spin correlations are considered near the surface of a semi-infinite spin-$\frac12$ Heisenberg antiferromagnet on a simple cubic lattice. In the spin-wave approximation, the excitation spectrum of this model involves bulk…

Strongly Correlated Electrons · Physics 2015-05-13 N. Voropajeva , A. Sherman

Composite multiferroics, heterostructures of ferromagnetic (FM) and ferroelectric (FE) materials, are characterized by a remarkable magnetoelectric effect at the interface. Previous work has supported the ferromagnetic structure with…

Mesoscale and Nanoscale Physics · Physics 2016-04-01 Zidong Wang , Malcolm J. Grimson

The ferromagnetism of a thin GaMnAs layer with a perpendicular easy anisotropy axis is investigated by means of several techniques, that yield a consistent set of data on the magnetic properties and the domain structure of this diluted…

In a two or three dimensional ferromagnetic XXZ model, a low energy excitation mode above a magnetic domain wall is gapless, whereas all of the usual spin wave excitations moving around the whole crystal are gapful. Although this surprising…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Tohru Koma , Masanori Yamanaka
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