845 research outputs found
Magnetic order and frustrated dynamics in Li(Ni0.8Co0.1Mn0.1)O2: a study by {\mu}+SR and SQUID magnetometry
Recently, the mixed transition metal oxides of the form Li(Ni1-y-zCoyMnz)O2,
have become the center of attention as promising candidates for novel battery
material. These materials have also revealed very interesting magnetic
properties due to the alternate stacking of planes of metal oxides on a 2D
triangular lattice and the Li-layers. The title compound,
Li(Ni0.8Co0.1Mn0.1)O2, has been investigated by both magnetometry and
measurements and {\mu}+SR. We find the evolution of localized magnetic moments
with decreasing temperature below 70 K. The magnetic ground state (T = 2 K) is,
however, shown to be a frustrated system in 3D, followed by a transition into a
possible 2D spinglass above 22 K. With further increasing temperature the
compound show the presence of remaining correlations with increasing effective
dimensionality all the way up to the ferrimagnetic transition at TC = 70 K.Comment: Accepted for publication in Physics Procedia (muSR2011 Conference
Lithium Diffusion & Magnetism in Battery Cathode Material LixNi1/3Co1/3Mn1/3O2
We have studied low-temperature magnetic properties as well as
high-temperature lithium ion diffusion in the battery cathode materials
LixNi1/3Co1/3Mn1/3O2 by the use of muon spin rotation/relaxation. Our data
reveal that the samples enter into a 2D spin-glass state below TSG=12 K. We
further show that lithium diffusion channels become active for T>Tdiff=125 K
where the Li-ion hopping-rate [nu(T)] starts to increase exponentially.
Further, nu(T) is found to fit very well to an Arrhenius type equation and the
activation energy for the diffusion process is extracted as Ea=100 meV.Comment: Submitted to Journal of Physics: Conference Series (2014
Magnetic Order in the 2D Heavy-Fermion System CePt2In7 studied by muSR
The low-temperature microscopic magnetic properties of the quasi-2D
heavyfermion compound, CePt2In7 are investigated by using a positive muon-spin
rotation and relaxation (?muSR) technique. Clear evidence for the formation of
a commensurate antiferromagnetic order below TN=5.40 K is presented. The
magnetic order parameter is shown to fit well to a modified BSC gap-energy
function in a strong-coupling scenario.Comment: Accepted in Journal of Physics: Conference Series (2014
Electronic structure near the 1/8-anomaly in La-based cuprates
We report an angle resolved photoemission study of the electronic structure
of the pseudogap state in \NdLSCO ( K). Two opposite dispersing Fermi
arcs are the main result of this study. The several scenarios that can explain
this observation are discussed.Comment: A high-resolution version can be found at
http://lns.web.psi.ch/lns/download/Pockets/arXiv.pd
Spectroscopic evidence for preformed Cooper pairs in the pseudogap phase of cuprates
Angle-resolved photoemission on underdoped LaSrCuO
reveals that in the pseudogap phase, the dispersion has two branches located
above and below the Fermi level with a minimum at the Fermi momentum. This is
characteristic of the Bogoliubov dispersion in the superconducting state. We
also observe that the superconducting and pseudogaps have the same d-wave form
with the same amplitude. Our observations provide direct evidence for preformed
Cooper pairs, implying that the pseudogap phase is a precursor to
superconductivity
Five-Dimensional Gauge Theories and Quantum Mechanical Matrix Models
We show how the Dijkgraaf-Vafa matrix model proposal can be extended to
describe five-dimensional gauge theories compactified on a circle to four
dimensions. This involves solving a certain quantum mechanical matrix model. We
do this for the lift of the N=1* theory to five dimensions. We show that the
resulting expression for the superpotential in the confining vacuum is
identical with the elliptic superpotential approach based on Nekrasov's
five-dimensional generalization of Seiberg-Witten theory involving the
relativistic elliptic Calogero-Moser, or Ruijsenaars-Schneider, integrable
system.Comment: 11 pages, 2 figures, JHEP3.cls, important references adde
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