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The observed magnetic field on the solar surface is characterized by a very complex spatial and temporal behavior. Although feature-tracking algorithms have allowed us to deepen our understanding of this behavior, subjectivity plays an…

We have observed localized spin-wave modes in individual thin-film ferromagnetic wires using time-resolved Kerr microscopy as a micron-scale spectroscopic probe. The localization is due to the partial demagnetization of a wire when an…

Materials Science · Physics 2009-11-07 J. P. Park , P. Eames , D. M. Engebretson , J. Berezovsky , P. A. Crowell

An applied magnetic field affects a superconductor in two ways -- by promoting pairing fluctuations, and by inducing topological defects called vortices that carry quantized magnetic flux. A quantitative characterization of the resultant…

Superconductivity · Physics 2026-03-19 Jiajie Cheng , Jaewon Kim , Oriana K. Diessel , Chong Zu , Shubhayu Chatterjee

Time-resolved Kerr microscopy is used to study the excitations of individual micron- scale ferromagnetic thin film elements in their remnant state. Thin (18 nm) square elements with edge dimensions between 1 and 10 $\mu$m form closure…

Materials Science · Physics 2009-11-07 J. P. Park , P. Eames , D. M. Engebretson , J. Berezovsky , P. A. Crowell

We derive an equilibrium statistical theory for the macroscopic description of a ferromagnetic material at positive finite temperatures. Our formulation describes the most-probable equilibrium macrostates that yield a coherent deterministic…

Materials Science · Physics 2007-05-23 Markos A. Katsoulakis , Petr Plechac

Strong spin fluctuations are expected near the thermodynamic critical point of a continuous magnetic phase transition. Such critical spin fluctuations are highly correlated and in principle can occur at any time- and length-scales; they…

Mesoscale and Nanoscale Physics · Physics 2020-07-24 Chenhao Jin , Zui Tao , Kaifei Kang , Kenji Watanabe , Takashi Taniguchi , Kin Fai Mak , Jie Shan

We suggest to use `fluctuation spectroscopy' as a method to detect granularity in a disordered metal close to a superconducting transition. We show that with lowering temperature $T$ the resistance $R(T)$ of a system of relatively large…

Superconductivity · Physics 2008-03-26 I. V. Lerner , A. A. Varlamov , V. M. Vinokur

We develop an effective low-frequency theory of the electromagnetic field in equilibrium with thermal objects. The aim is to compute thermal magnetic noise spectra close to metallic microstructures. We focus on the limit where the material…

Mesoscale and Nanoscale Physics · Physics 2009-10-17 Carsten Henkel

The higher order moments of the fluctuations for the thermodynamical systems in the presence of fields are investigated in the framework of a theoretical method. The metod uses a generalized statistical ensemble consonant with the adequate…

Statistical Mechanics · Physics 2009-11-07 A. Boer , S. Dumitru

Spin fluctuations are an important issue for the design and operation of future spintronic devices. Femtosecond noise correlation spectroscopy (FemNoC) was recently applied to detect ultrafast magnetization fluctuations. FemNoC gives direct…

Magnetic microscopy that combines nanoscale spatial resolution with picosecond scale temporal resolution uniquely enables direct observation of the spatiotemporal magnetic phenomena that are relevant to future high-speed, high-density…

Mesoscale and Nanoscale Physics · Physics 2021-07-07 Chi Zhang , Jason M. Bartell , Jonathan C. Karsch , Isaiah Gray , Gregory D. Fuchs

A quantum mechanical model is used to derive a generalized Landau-Lifshitz equation for a magnetic moment, including fluctuations and dissipation. The model reproduces the Gilbert-Brown form of the equation in the classical limit. The…

Materials Science · Physics 2009-11-07 A. Rebei , G. J. Parker

We present a systematic numerical modeling investigation of magnetization dynamics and thermal magnetic moment fluctuations of single magnetic domain nanoparticles in a configuration applicable to enhancing inductive magnetic resonance…

Mesoscale and Nanoscale Physics · Physics 2021-06-16 Tahmid Kaisar , Md Mahadi Rajib , Hatem ElBidweihy , Mladen Barbic , Jayasimha Atulasimha

We have a choice of methods for examining domains at the surface of a ferromagnet that depend on probing the stray field distribution, but these methods do not work in antiferromagnets or compensated ferrimagnets, which produce no stray…

Materials Science · Physics 2018-12-14 K. E. Siewierska , N. Teichert , R. Schäfer , J. M. D. Coey

Magneto-optical sensors including spin noise spectroscopies and magneto-optical Kerr effect microscopies are now ubiquitous tools for materials characterization that can provide new understanding of spin dynamics, hyperfine interactions,…

Quantum Physics · Physics 2022-02-10 Yun-Yi Pai , Claire E. Marvinney , Chengyun Hua , Raphael C. Pooser , Benjamin J. Lawrie

We report new experimental results obtained onthe insulating spin glass CdCrInS_4. Our experimental setup allows a quantitative comparison between thethermo-remanent magnetization and the autocorrelation of spontaneous fluctuations of…

Disordered Systems and Neural Networks · Physics 2009-11-10 Didier Herisson , Miguel Ocio

We suggest an approach to account for spatial (composition) and thermal fluctuations in "disordered" magnetic models (e.g. Heisenberg, Ising) with given spatial dependence of magnetic spin-spin interaction. Our approach is based on…

Disordered Systems and Neural Networks · Physics 2016-08-16 Yu. G. Semenov , V. A. Stephanovich

When probing nuclear spins in materials on the nanometer scale, random fluctuations of the spin polarization will exceed the mean Boltzmann polarization for sample volumes below about (100nm)^3. In this work, we use magnetic resonance force…

Mesoscale and Nanoscale Physics · Physics 2008-01-14 C. L. Degen , M. Poggio , H. J. Mamin , D. Rugar

The spatial mode is an essential component of an electromagnetic field description, yet it is challenging to characterize it for optical fields with low average photon number, such as in a squeezed vacuum. We present a method for…

A general scheme is developed to analyze the effect of non-uniform thermal magnetization fluctuations in a thin film. The normal mode formalism is utilized to calculate random magnetization fluctuations. The magnetization noise is…

Statistical Mechanics · Physics 2009-11-07 Vladimir L. Safonov , H. Neal Bertram