Enhancement of the electronic contribution to the low-temperature specific heat of an Fe/Cr magnetic multilayer

Abstract

We measured the low temperature specific heat of a sputtered (F e 23Å /Cr 12Å ) 33 magnetic multilayer, as well as separate 1000Å thick Fe and Cr films. Magnetoresistance and magnetization measurements on the multilayer demonstrated antiparallel coupling between the Fe layers. Using microcalorimeters made in our group, we measured the specific heat for 4 < T < 30 K and in magnetic fields up to 8 T for the multilayer. The low temperature electronic specific heat coefficient of the multilayer in the temperature range 4 < T < 14 K is γ M L = 8.4 mJ/K 2 g − at. This is significantly larger than that measured for the Fe or Cr films (5.4 and. 3.5 mJ/K 2 mol respectively). No magnetic field dependence of γ M L was observed up to 8 T .These results can be explained by a softening of the phonon modes observed in the same data and the presence of an Fe-Cr alloy phase at the interfaces.75.70 (magnetic multilayer), 75.40 (specific heat of magnetic materials) Typeset using REVT E X 1

Ab initioelectronic structure calculations of correlated systems: An EMTO-DMFT approach

“…40 Experimentally it was found that the magnetic multilayers grown epitaxially shows an enhancement of the electronic contribution to the low-temperature specific heat. 41 Standard electronic band-structure calculations could not reproduce this enhancement, 42 which can be an evidence of the correlation effects. Our aim is to check whether the correlation effects considered in the EMTO-DMFT approach can lead to an essential renormalization of the density of states at the Fermi level N(E F ).…”

Thermal and electrical conductivity of approximately 100-nm permalloy, Ni, Co, Al, and Cu films and examination of the Wiedemann-Franz Law

“…[62][63][64][65][66] Such a shift could reduce the probability of the largeangle phonon scattering events required to return L (T ) to the Sommerfeld value at high T, thereby requiring higher temperatures to finally reenter the WF regime. However, our calculations suggest that the shifts in phonon DOS required to explain the ∼ 20% reduction in L seen here are so large that they would drive deviations of the heat capacity away from bulk-like values, in contrast to experimental data showing very good agreement between bulk and even very thin Au and Cu films.…”

Electronic and magnetic properties of bimetallicL10cuboctahedral clusters by means of fully relativistic density-functional-based calculations

“…Focusing in the field of magnetic recording, a huge amount of experimental and theoretical work has been carried out during the last decade to seek novel approaches to construct advanced materials for ultrahigh density magnetic storage, with the aim of increasing the state-of-the-art beyond 1 Tbit/in 2( [8,[12][13][14][15] ) . Most approaches are focused on thin films or multilayers [16][17][18] and recently on slabs [19]. However, during the last decade has emerged the possibility to use clusters deposited on surfaces [20][21][22][23][24][25][26] to increase the recording density.…”