Polaronic heat capacity in the Anderson-Hasegawa model

Abstract

An exact treatment of the Anderson -Hasegawa two -site model, incorporating the presence of superexchange and polarons, is used to compute the heat capacity. The calculated results point to the dominance of the lattice contribution, especially in the ferromagnetic regime. This behavior is in qualitative agreement with experimental findings. 1 The Anderson-Hasegawa (AH) model [1] is a two-site realization of the basic idea of double -exchange (DE) proposed by Zener [2] almost fifty years ago. In the DE scenario a localized spin is visualized to be strongly 'Hund's rule' coupled to an itinerant spin at the same site governed by strength J H , whereas the itinerant spin can tunnel from site to site accompanied by a 'hopping integral' t. Because of large J H the itinerant spin is polarized along the localized spin, and as it hops to a neighboring site, it carries with it the memory of its spin polarization, thereby polarizing the neighboring local spin as well. Thus transport is correlated with spin ordering of localized moments, leading to concomitant metal-insulator transition and magnetic ordering.

IRIDE: Interdisciplinary research infrastructure based on dual electron linacs and lasers

“…The internal architecture of fibrin fibers, the basic constituent of blood cloths and thrombi, has also been intensively investigated [31]. Indeed one of the therapeutic approaches in the treatment of patients suffering from acute myocardial infarction (and, in general, with thromboembolic diseases) is based on the use of thrombolitic drugs that promote clot lysis.…”

“…The last undulator can be tuned at higher harmonics of the fundamental, and coherent radiation up to 1.83 nm can be obtained. The operation at full energy of one LINAC (1.5 GeV) would allow SASE radiation in first harmonic up to 6.8 nm, but the number of undulators of the main section should be brought to 14, since for the operation at 3 GeV a significantly longer undulator chain is required (30)(31)(32)(33)(34)(35). This number can be reduced according the peak values of the current, which can be obtained.…”

Local chemical distribution and electronic structure of Ge1−T DMS single crystals (T=Cr, Mn, Fe)

“…compares the Mn 2p XAS spectrum of Ge 0.94 Mn 0.06 to those of reference Mn compounds having formal Mn valences of 2+ MnO[11], 4+ MnO 2[11], Mn metal[12], and Mn x Ge y alloy. According to XRD, Mn x Ge y alloy actually consists of several Mn-rich Mn x Ge y alloy phases.…”

PES and XAS studies of Mn12-Ac molecular magnet

“…[9], and Ref. [8], respectively, and shifted by À0:9; 0.7 and À1:8 eV; respectively. The Mn 2p 3=2 XAS spectrum of Mn12-Ac shows three sharp structures (labeled as A, B, C).…”

“…The data for MnO (Mn 2þ ), Mn 2 O 3 ðMn 3þ ), and MnO 2 ðMn 4þ ) were reproduced from Ref. [8], Ref. [9], and Ref.…”