19 research outputs found
Electronic, magnetic and transport properties of Fe intercalated 2H-TaS studied by means of the KKR-CPA method
The electronic, magnetic and transport properties of Fe intercalated
2H-TaS have been investigated by means of the Korringa-Kohn-Rostoker (KKR)
method. The non-stoichiometry and disorder in the system has been accounted for
using the Coherent Potential Approximation (CPA) alloy theory. A pronounced
influence of disorder on the spin magnetic moment has been found for the
ferro-magnetically ordered material. The same applies for the spin-orbit
induced orbital magnetic moment and magneto-crystalline anisotropy energy. The
temperature-dependence of the resistivity of disordered 2H-FeTaS
investigated on the basis of the Kubo-St\v{r}eda formalism in combination with
the alloy analogy model has been found in very satisfying agreement with
experimental data. This also holds for the temperature dependent anomalous Hall
resistivity . The role of thermally induced lattice
vibrations and spin fluctuations for the transport properties is discussed in
detail
Spin-orbit induced longitudinal spin-polarized currents in non-magnetic solids
For certain non-magnetic solids with low symmetry the occurrence of
spin-polarized longitudinal currents is predicted. These arise due to an
interplay of spin-orbit interaction and the particular crystal symmetry. This
result is derived using a group-theoretical scheme that allows investigating
the symmetry properties of any linear response tensor relevant to the field of
spintronics. For the spin conductivity tensor it is shown that only the
magnetic Laue group has to be considered in this context. Within the introduced
general scheme also the spin Hall- and additional related transverse effects
emerge without making reference to the two-current model. Numerical studies
confirm these findings and demonstrate for (AuPt)Sc that
the longitudinal spin conductivity may be in the same order of magnitude as the
conventional transverse one. The presented formalism only relies on the
magnetic space group and therefore is universally applicable to any type of
magnetic order.Comment: 5 pages, 1 table, 2 figures (3 & 2 subfigures
Calculating linear response functions for finite temperatures on the basis of the alloy analogy model
A scheme is presented that is based on the alloy analogy model and allows to
account for thermal lattice vibrations as well as spin fluctuations when
calculating response quantities in solids. Various models to deal with spin
fluctuations are discussed concerning their impact on the resulting temperature
dependent magnetic moment, longitudinal conductivity and Gilbert damping
parameter. It is demonstrated that using the Monte Carlo (MC) spin
configuration as an input, the alloy analogy model is capable to reproduce
results of MC simulations on the average magnetic moment within all spin
fluctuation models under discussion. On the other hand, response quantities are
much more sensitive to the spin fluctuation model. Separate calculations
accounting for either the thermal effect due to lattice vibrations or spin
fluctuations show their comparable contributions to the electrical conductivity
and Gilbert damping. However, comparison to results accounting for both thermal
effects demonstrate violation of Matthiessen's rule, showing the non-additive
effect of lattice vibrations and spin fluctuations. The results obtained for
bcc Fe and fcc Ni are compared with the experimental data, showing rather good
agreement for the temperature dependent electrical conductivity and Gilbert
damping parameter
The temperature dependence of FeRh's transport properties
The finite-temperature transport properties of FeRh compounds are
investigated by first-principles Density Functional Theory-based calculations.
The focus is on the behavior of the longitudinal resistivity with rising
temperature, which exhibits an abrupt decrease at the metamagnetic transition
point, between ferro- and antiferromagnetic phases. A detailed
electronic structure investigation for K explains this feature and
demonstrates the important role of (i) the difference of the electronic
structure at the Fermi level between the two magnetically ordered states and
(ii) the different degree of thermally induced magnetic disorder in the
vicinity of , giving different contributions to the resistivity. To
support these conclusions, we also describe the temperature dependence of the
spin-orbit induced anomalous Hall resistivity and Gilbert damping parameter.
For the various response quantities considered the impact of thermal lattice
vibrations and spin fluctuations on their temperature dependence is
investigated in detail. Comparison with corresponding experimental data finds
in general a very good agreement
The temperature dependence of FeRh’s transport properties
The finite-temperature transport properties of FeRh compounds are investigated by first-principles
Density Functional Theory-based calculations. The focus is on the behavior of the longitudinal resistivity
with rising temperature, which exhibits an abrupt decrease at the metamagnetic transition
point, T = Tm between ferro- and antiferromagnetic phases. A detailed electronic structure investigation
for T ≥ 0 K explains this feature and demonstrates the important role of (i) the difference
of the electronic structure at the Fermi level between the two magnetically ordered states and (ii)
the different degree of thermally induced magnetic disorder in the vicinity of Tm, giving different
contributions to the resistivity. To support these conclusions, we also describe the temperature
dependence of the spin-orbit induced anomalous Hall resistivity and Gilbert damping parameter.
For the various response quantities considered the impact of thermal lattice vibrations and spin fluctuations
on their temperature dependence is investigated in detail. Comparison with corresponding
experimental data finds in general a very good agreement
Efficient Spin Injector Scheme Based on Heusler Materials
We present a rational design scheme intended to provide stable high spin polarization at the interfaces of the magnetoresistive junctions by fulfilling the criteria of structural and chemical compatibilities at the interface. This can be realized by joining the semiconducting and half-metallic Heusler materials with similar structures. The present first-principles calculations verify that the interface remains half-metallic if the nearest interface layers effectively form a stable Heusler material with the properties intermediately between the surrounding bulk parts. This leads to a simple rule for selecting the proper combinations