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We propose nanoscale magnetometry via isolated single-spin qubits as a probe of superconductivity in two-dimensional materials. We characterize the magnetic field noise at the qubit location, arising from current and spin fluctuations in…

Ground-state fluctuations reduce the zero-temperature magnetic moments of the spins in a quantum antiferromagnet. In the neighborhood of surfaces, interfaces, and other defects which break translational symmetry, these fluctuations are not…

Other Condensed Matter · Physics 2007-05-23 G. J. Mata , E. Pestana , M. Kiwi , H. Dreysse

We observe magnetization dynamics induced by spin momentum transfer in the noise spectra of current perpendicular to the plane giant magnetoresistance spin valves. The dynamics are observable only for those combinations of current direction…

Materials Science · Physics 2009-11-10 M. Covington , M. AlHajDarwish , Y. Ding , N. J. Gokemeijer , M. A. Seigler

We analyze shot noise in a magnetic tunnel junction with a two-level quantum dot attached to the magnetic electrodes. The considerations are limited to the case when some transport channels are suppressed at low temperatures. Coupling of…

Mesoscale and Nanoscale Physics · Physics 2017-01-10 T. Szczepanski , V. K. Dugaev , J. Barnas , I. Martinez , J. P. Cascales , J. -Y. Hong , M. -T. Lin , F. G. Aliev

We develop a time dependent random matrix theory describing the influence of a time-dependent perturbation on mesoscopic conductance fluctuations in open quantum dots. The effect of external field is taken into account to all orders of…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Maxim G. Vavilov , Igor L. Aleiner

A mesoscopic description of spin-transfer effect is proposed, based on the spin-injection mechanism occurring at the junction with a ferromagnet. The effect of spin-injection is to modify locally, in the ferromagnetic configuration space,…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 J. -E. Wegrowe , S. M. Santos , M. -C. Ciornei , H. -J. Drouhin , J. M. Rubí

The role of spin fluctuations near magnetic phase transitions is crucial for generating various exotic phenomena, including anomalies in the extraordinary Hall effect, excess spin-current generation through the spin-Hall effect (SHE), and…

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

We consider a model in which the quantum fluctuation can be controlled and show that the system responds to a spatially periodic external field at zero temperature. This signifies the occurrence of spatial stochastic resonance where the…

Statistical Mechanics · Physics 2009-11-07 Parongama Sen

The power spectrum of quantum fluctuations of the electromagnetic field produced by an elementary particle is determined. It is found that in a wide range of practically important frequencies the power spectrum of fluctuations exhibits an…

Data Analysis, Statistics and Probability · Physics 2009-11-11 Kirill A. Kazakov

In this note we study the block spin mean-field Potts model, in which the spins are divided into $s$ blocks and can take $q\ge 2$ different values (colors). Each block is allowed to contain a different proportion of vertices and behaves…

Probability · Mathematics 2022-03-09 Jonas Jalowy , Matthias Löwe , Holger Sambale

This is a study of phase-coherent conduction through a ballistic point contact with disordered leads. The disorder imposes mesoscopic (sample-to-sample) fluctuations and weak-localization corrections on the conductance, and also leads to…

Condensed Matter · Physics 2007-05-23 C. W. J. Beenakker , J. A. Melsen

Polarized neutron diffraction experiments on an organic magnetic material reveal a highly skewed distribution of spin density within the magnetic molecular unit. The very large magnitude of the observed effect is due to quantum spin…

Strongly Correlated Electrons · Physics 2015-06-25 A. Zheludev , V. O. Garlea , S. Nishihara , Y. Hosokoshi , A. Cousson , A. Gukasov , K. Inoue

The quantum excitations of the collective magnetization dynamics in a ferromagnet (F) - magnons - enable spin transport without an associated charge current. This pure spin current can be transferred to electrons in an adjacent non-magnetic…

Mesoscale and Nanoscale Physics · Physics 2016-07-20 Akashdeep Kamra , Wolfgang Belzig

The zero-temperature physics of interacting quantum dots attached to superconducting leads is now well understood. The overall qualitative picture is obtained from the static mean-field approximation. The situation drastically changes at…

Strongly Correlated Electrons · Physics 2024-06-12 Václav Janiš , Jiawei Yan

Fluctuations of electric fields can change the position of a gate-defined quantum dot in a semiconductor heterostructure. In the presence of magnetic field gradient, these stochastic shifts of electron's wavefunction lead to fluctuations of…

Mesoscale and Nanoscale Physics · Physics 2024-08-09 Marcin Kępa , Łukasz Cywiński , Jan A. Krzywda

We investigate the angular dependence of the spin torque generated when applying a temperature difference across a spin-valve. Our study shows the presence of a non-trivial fixed point in this angular dependence, i.e. the possibility for a…

Mesoscale and Nanoscale Physics · Physics 2014-10-29 David Luc , Xavier Waintal

Fluctuations of local fields cause decoherence of quantum objects. It is generally believed that at high temperatures, thermal noises are much stronger than quantum fluctuations unless the thermal effects are suppressed by certain…

Quantum Physics · Physics 2011-10-04 Xin-Yu Pan , Gang-Qin Liu , Dong-Qi Liu , Zhan-Feng Jiang , Nan Zhao , Ren-Bao Liu

We demonstrate that shot noise in Fe/MgO/Fe/MgO/Fe double-barrier magnetic tunnel junctions is determined by the relative magnetic configuration of the junction and also by the asymmetry of the barriers. The proposed theoretical model,…

Mesoscale and Nanoscale Physics · Physics 2012-09-21 J. P. Cascales , D. Herranz , F. G. Aliev , T. Szczepanski , V. K. Dugaev , J. Barnas , A. Duluard , M. Hehn , C. Tiusan

We describe spin transfer in a ferromagnet/normal metal/ferromagnet spin-valve point contact. Spin is transferred from the spin-polarized device current to the magnetization of the free layer by the mechanism of incoherent magnon emission…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 V. I. Kozub , J. Caro