6 research outputs found
Physical properties of CeGe2-x (x = 0.24) single crystals
We present data on the anisotropic magnetic properties, heat capacity and
transport properties of CeGe2-x (x = 0.24) single crystals. The electronic
coefficient of the heat capacity, gamma ~ 110 mJ/mol K^2, is enhanced; three
magnetic transitions, with critical temperatures of ~ 7 K, ~ 5 K, and ~ 4 K are
observed in thermodynamic and transport measurements. The ground state has a
small ferromagnetic component along the c - axis. Small applied field, below 10
kOe, is enough to bring the material to an apparent saturated paramagnetic
state (with no further metamagnetic transitions up to 55 kOe) with a reduced,
below 1 mu_B, saturated moment
Spin-Polarized Current Induced Torque in Magnetic Tunnel Junctions
We present tight-binding calculations of the spin torque in non-collinear
magnetic tunnel junctions based on the non-equilibrium Green functions
approach. We have calculated the spin torque via the effective local magnetic
moment approach and the divergence of the spin current. We show that both
methods are equivalent, i.e. the absorption of the spin current at the
interface is equivalent to the exchange interaction between the electron spins
and the local magnetization. The transverse components of the spin torque
parallel and perpendicular to the interface oscillate with different phase and
decay in the ferromagnetic layer (FM) as a function of the distance from the
interface. The period of oscillations is inversely proportional to the
difference between the Fermi-momentum of the majority and minority electrons.
The phase difference between the two transverse components of the spin torque
is due to the precession of the electron spins around the exchange field in the
FM layer. In absence of applied bias and for a relatively thin barrier the
perpendicular component of the spin torque to the interface is non-zero due to
the exchange coupling between the FM layers across the barrier.Comment: 6 pages, 3 figure
Spin Transfer Switching and Spin Polarization in Magnetic Tunnel Junctions with Mgo and Alox Barriers
We present spin transfer switching results for MgO based magnetic tunneling
junctions (MTJs)with large tunneling magnetoresistance (TMR) ratio of up to
150% and low intrinsic switching current density of 2-3 x 10 MA/cm2. The
switching data are compared to those obtained on similar MTJ nanostructures
with AlOx barrier. It is observed that the switching current density for MgO
based MTJs is 3-4 times smaller than that for AlOx based MTJs, and that can be
attributed to higher tunneling spin polarization (TSP) in MgO based MTJs. In
addition, we report a qualitative study of TSP for a set of samples, ranging
from 0.22 for AlOx to 0.46 for MgO based MTJs, and that shows the TSP (at
finite bias) responsible for the current-driven magnetization switching is
suppressed as compared to zero-bias tunneling spin polarization determined from
TMR.Comment: To appear in Appl. Phys. Lett. soo
Physical properties of CeGe2-x (x=0.24) single crystals
We present data on the anisotropic magnetic properties, heat capacity and transport properties of CeGe2−x (x = 0.24) single crystals. The electronic coefficient of the heat capacity, γ ~ 110 mJ mol−1 K−2, is enhanced; three magnetic transitions, with critical temperatures of ≈7, ≈5 and ≈4 K are observed in thermodynamic and transport measurements. The ground state has a small ferromagnetic component along the c-axis. Small applied field, below 10 kOe, is enough to bring the material to an apparent saturated paramagnetic state (with no further metamagnetic transitions up to 55 kOe) with a reduced, below 1.2μB, saturated moment.This is the version of the article before peer review or editing, as submitted by an author to Journal of Physics: Condensed Matter. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at DOI: 10.1088/0953-8984/26/14/146005. Posted with permission.</p