نتایج جستجو برای: magnetic cooling
تعداد نتایج: 390166 فیلتر نتایج به سال:
We report on the magnetic phases of quasi-two dimensional Rb F = 1 spinor gases produced by cooling unmagnetized gases into the regime of quantum degeneracy. We find a robust low temperature magnetic phase characterized by crystalline ordering of spin domains, an instance of spontaneously broken translational symmetry in a quantum fluid. This phase displays an emergent order parameter, a spin a...
We demonstrate dynamical nuclear-spin polarization in the absence of an external magnetic field by resonant circularly polarized optical excitation of a single electron or hole charged quantum dot. Optical pumping of the electron spin induces an effective inhomogeneous magnetic (Knight) field that determines the direction along which nuclear spins could polarize and enables nuclear-spin cooling...
The limited thermomagnetic instabilities in the critical state have been investigated in hard superconductors under an incomplete penetration of the magnetic flux into the sample and under different external cooling conditions. A flat plate is considered in an external magnetic field parallel to the plate surface. Conditions have been found under which it is possible to observe the electric fie...
Electron cooling is a well established method to obtain ion beams of high phase space density or to reduce the kinetic energy of ions in traps. To improve its theoretical understanding we investigated the underlying microscopic physics of the energy transfer in individual ion-electron interactions in the presence of a homogeneous magnetic field. This has been done both by analytic perturbative ...
Recent observations of the compact source embedded within the supernova remnant RCW 103 rekindle interest in the origin of this object’s emission. We contrast several models in which neutron-star cooling powers RCW 103. Specifically, either the presence of an accreted envelope or a sufficiently intense magnetic field can account for the X-ray emission from this object. Subject headings: stars: ...
A solid-state implementation of a quantum computer composed entirely of silicon is proposed. Qubits are 29Si nuclear spins arranged as chains in a 28Si (spin-0) matrix with Larmor frequencies separated by a large magnetic field gradient. No impurity dopants or electrical contacts are needed. Initialization is accomplished by optical pumping, algorithmic cooling, and pseudo-pure state techniques...
Recent observations of the compact source embedded within the supernova remnant RCW 103 rekindle interest in the origin of this object’s emission. We contrast several models in which neutron-star cooling powers RCW 103. Specifically, either the presence of an accreted envelope or a sufficiently intense magnetic field can account for the X-ray emission from this object. Subject headings: stars: ...
Molecular nanomagnets are considered valid candidates for magnetic refrigeration at low temperatures. Designing these materials for enhanced cooling requires the control and optimization of the quantum properties at the molecular level, in particular: spin ground state, magnetic anisotropy, and presence of low-lying excited spin states. Herein, we present the theoretical framework together with...
Bose-Einstein condensation in a dilute gas of sodium atoms has been observed. The atoms were trapped in an optically plugged magnetic trap or in a cloverleaf magnetic trap. Rf induced evaporative cooling increased the phase-space density by six orders of magnitude. We summarize the different techniques used, and discuss recent studies of properties of Bose condensates with an outlook on future ...
The polycrystalline manganite La0.75Sr0.25MnO3 prepared by an alternative carbonate precipitation route reveals the rhombohedral perovskite structure. Magnetization isotherms measured up to 2 T are used to determine Curie temperature of 332 K by means of Arrott plot. Maximum of magnetic entropy change is found at Curie temperature. The relative cooling power equal to 64 J/kg for 1.5 T magnetic ...
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