11,473 research outputs found
Direct observation of pinned/biased moments in magnetic superlattices
We report the \QTR{it}{pinned/biased} \QTR{it}{moment} in the superlattices
consisting of ferromagnetic (FM) SrRuO and antiferromgnetic (AFM)
SrMnO. This superlattice system shows anisotropy and oriented
pinning/biasing in the field-cooled (FC) hysteresis loop. The in-plane
cooling-field provides antiferromagnetic orientations while out-of-plane
cooling-field provides ferromagnetic orientations to the pinned/biased moments.
The spacer layer thickness, strength and orientation of magnetic field, cooling
field, and driving current influence the pinning strength. We propose that the
magnetic structure is a repetition of ()/ unit below a
critical field to explain its magnetic and transport properties. The transport
behavior is discussed using the spin-dependent conduction.Comment: to be published in Physical Review
Conservativeness of non-symmetric diffusion processes generated by perturbed divergence forms
Let E be an unbounded open (or closed) domain in Euclidean space of dimension
greater or equal to two. We present conservativeness criteria for (possibly
reflected) diffusions with state space E that are associated to fairly general
perturbed divergence form operators. Our main tool is a recently extended
forward and backward martingale decomposition, which reduces to the well-known
Lyons-Zheng decomposition in the symmetric case.Comment: Corrected typos, minor modification
Numerical Study of TAP Metastable States in 3-body Ising Spin Glasses
The distribution of solutions of the Thouless-Anderson-Palmer equation is
studied by extensive numerical experiments for fully connected 3-body
interaction Ising spin glass models in a level of annealed calculation. A
recent study predicted that when the equilibrium state of the system is
characterized by one-step replica symmetry breaking, the distribution is
described by a Becchi-Rouet-Stora-Tyutin (BRST) supersymmetric solution in the
relatively low free energy region, whereas the BRST supersymmetry is broken for
higher values of free energy (Crisanti et al., Phys. Rev. B 71 (2005) 094202).
Our experiments qualitatively reproduce the discriminative behavior of
macroscopic variables predicted by the theoretical assessment.Comment: 13 pages, 4 figure
Poly(ADP-Ribose) Polymerase 1 Accelerates Single-Strand Break Repair in Concert with Poly(ADP-Ribose) Glycohydrolase
Single-strand breaks are the commonest lesions arising in cells, and defects in their repair are implicated in neurodegenerative disease. One of the earliest events during single-strand break repair (SSBR) is the rapid synthesis of poly(ADP-ribose) (PAR) by poly(ADP-ribose) polymerase (PARP), followed by its rapid degradation by poly(ADP-ribose) glycohydrolase (PARG). While the synthesis of poly(ADP-ribose) is important for rapid rates of chromosomal SSBR, the relative importance of poly(ADP-ribose) polymerase 1 (PARP-1) and PARP-2 and of the subsequent degradation of PAR by PARG is unclear. Here we have quantified SSBR rates in human A549 cells depleted of PARP-1, PARP-2, and PARG, both separately and in combination. We report that whereas PARP-1 is critical for rapid global rates of SSBR in human A549 cells, depletion of PARP-2 has only a minor impact, even in the presence of depleted levels of PARP-1. Moreover, we identify PARG as a novel and critical component of SSBR that accelerates this process in concert with PARP-1
The intrinsic strangeness and charm of the nucleon using improved staggered fermions
We calculate the intrinsic strangeness of the nucleon, - ,
using the MILC library of improved staggered gauge configurations using the
Asqtad and HISQ actions. Additionally, we present a preliminary calculation of
the intrinsic charm of the nucleon using the HISQ action with dynamical charm.
The calculation is done with a method which incorporates features of both
commonly-used methods, the direct evaluation of the three-point function and
the application of the Feynman- Hellman theorem. We present an improvement on
this method that further reduces the statistical error, and check the result
from this hybrid method against the other two methods and find that they are
consistent. The values for and found here, together with
perturbative results for heavy quarks, show that dark matter scattering through
Higgs-like exchange receives roughly equal contributions from all heavy quark
flavors.Comment: 17 pages, 14 figure
31P-NMR and muSR Studies of Filled Skutterudite Compound SmFe4P12: Evidence for Heavy Fermion Behavior with Ferromagnetic Ground State
The 31P-NMR (nuclear magnetic resonance) and muSR (muon spin relaxation)
measurements on the filled skutterudite system SmFe4P12 have been carried out.
The temperature T dependence of the 31P-NMR spectra indicates the existence of
the crystalline electric field effect splitting of the Sm3+$ (J = 5/2)
multiplet into a ground state and an excited state of about 70 K. The
spin-lattice relaxation rate 1/T1 shows the typical behavior of the Kondo
system, i.e., 1/T1 is nearly T independent above 30 K, and varies in proportion
to T (the Korringa behavior, 1/T1 \propto T) between 7.5 K and 30 K. The T
dependence deviated from the Korringa behavior below 7 K, which is independent
of T in the applied magnetic field of 1 kOe, and suppressed strongly in higher
fields. The behavior is explained as 1/T1is determined by ferromagnetic
fluctuations of the uncovered Sm3+ magnetic moments by conduction electrons.
The muSR measurements in zero field show the appearance of a static internal
field associated with the ferromagnetic order below 1.6 K.Comment: 6 pages, 9 figures, to be published in J. Phys. Soc. Jpn. 75 (2006
Anisotropic pinned/biased magnetization in superlattices
The exchange coupling at the interfaces of magnetic superlattices consisting
of ferromagnetic and antiferromagnetic grown on (001)
oriented is studied with in-plane and out-of-plane orientations, with
respect to the substrate plane, of the cooling magnetic field. The
magnetization of the in-plane, field cooled hysteresis loop is lower than the
corresponding in-plane zero-field-cooled hysteresis loop. The out-of-plane
field cooled hysteresis loop is shifted, from the origin, along the graphical
magnetization axis. We attribute this irreversible rotation of the moment to
the pinning/biasing of spin in the layer in the vicinity of
interfaces by the antiferromagnetic layer.Comment: To be published in Eur. Jour. Phys. B for a topical issue on "new
trends in magnetic exchange bias phenomena
- …