Iron nanowires with a square cross section are grown by pulsed electrodeposition within a newly developed nanochannel template that allows for easy characterization. Measurements of the magnetoresistance as a function of magnetic field and temperature are performed within a large parameter window allowing for the investigation of the magnonic contribution to the magnetoresistance of electrodeposited iron nanowires. Values for the temperature dependent magnon stiffness D (T) are extracted: D (T) = D0(1 – d1T2) = 365(1 – 4.4 × 10–6 · T2 · K–2) meV Å2.
The weakly interacting quasiparticle picture of a Fermi liquid proposed by Landau (the phonon‐mediated electron‐pairing theory of Bardeen–Cooper–Schrieffer) provided a coherent theoretical basis for understanding how the interactions between electrons affect the low‐temperature properties of metals (metallic superconductors) for the past five decades. However, in recent years, strong departures from the predictions of these theories have been observed in an increasingly large number of systems, particularly in the vicinity of a quantum phase transition (QPT). This paper briefly reviews the current state of research in the areas of the non‐Fermi liquid (NFL) state, spin‐fluctuation‐mediated anisotropic superconductivity, and Bose–Einstein condensation (BEC) of magnons (bosonic quasiparticle excitations) near a quantum critical point (QCP), which is induced by external pressure or doping or nanocrystallite size or magnetic fields. 相似文献
Non-local, inhomogeneous and retarded response similar to that observed in experiments is studied theoretically by introducing the Inhomogeneous Momentum Average (IMA) approximation for single-polaron problems with disorder in the on-site potential and/or spatial variations of the electron-phonon couplings and/or phonon frequencies. We show that the electron-phonon coupling gives rise to an additional inhomogeneous, strongly retarded potential. This potential describes essential physics ignored by ”instanteneous” approximations. The accuracy of IMA is demonstrated by comparison with single-impurity results from the approximation-free Diagrammatic Monte Carlo (DMC) method. Its simplicity allows for easy study of many problems that were previously unaccessible.https://doi.org/10.1209/0295-5075/89/37007 相似文献
We study the nonlinear interfacial thermal transport across atomic junctions by the quantum self-consistent mean-field (QSCMF) theory based on the nonequilibrium Green's function approach; the QSCMF theory we propose is very precise and matches well with the exact results from quantum master equation. The nonlinearity at the interface is studied by effective temperature-dependent interfacial coupling calculated from the QSCMF theory. We find that nonlinearity can provide an extra channel for phonon transport in addition to the phonon scattering which usually blocks heat transfer. For weak linearly coupled interface, the nonlinearity can enhance the interfacial thermal transport; with increasing nonlinearity or temperature, the thermal conductance shows nonmonotonical behavior. The interfacial nonlinearity also induces thermal rectification, which depends on the mismatch of the two leads and also the interfacial linear coupling.https://doi.org/10.1209/0295-5075/103/64002 相似文献
Magnetophonon resonances induced by surface optical phonons are studied in both zero and nonzero dc current in n-doped graphene using the balance-equation scheme for nonlinear magnetotransport. At high temperature, obvious magnetophonon resonance in longitudinal resistivity can be observed. The observed single resonant peak at low mobility is composed of several main and minor peaks at high mobility. A novel peak position shift may be obtained for this system with nonequidistant Landau levels. For magnetophonon resonance in the presence of nonzero bias, the positions of resonant peaks shift and the oscillation becomes weak with an increase in drift velocity.https://doi.org/10.1209/0295-5075/103/37012 相似文献
We investigate a squeezed thermal spin state of nonlinear spin waves in Heisenberg ferromagnets. In this state, the magnon system possesses a new kind of quasiparticle, the dressed magnon, whose mass is a monotonically decreasing function of temperature. The noise of one spin component in the squeezed thermal spin state can be below the noise level in the vacuum state. The magnon system undergoes a first-order phase transition from the normal state to the squeezed thermal spin state. The critical temperature is much lower than the Curie temperature. A possible detection scheme based on a polarized neutron-scattering technique is suggested. 相似文献
It is shown how to generate stationary entanglement between light and microwave in a hybrid opto-electro-magnonical system which mainly consists of a microwave cavity, a yttrium iron garnet (YIG) sphere, and a nanofiber. The optical modes in nanofiber can evanescently be coupled to whispering gallery modes, that are able to interact with magnon mode via spin–orbit interaction, in YIG sphere, while the microwave cavity photons and magnons are coupled through magnetic dipole interaction simultaneously. Under reasonable parameter regimes, pretty amount of entanglement can be generated, and it also shows persistence against temperature. The present work is expected to provide a new perspective for building more advanced and comprehensive quantum networks along with magnons for fast-developing quantum technologies and for studying the macroscopic quantum phenomena. 相似文献
