47,084 research outputs found
Competing Ground States in Triple-layered Sr4Ru3O10: Verging on Itinerant Ferromagnetism with Critical Fluctuations
Sr4Ru3O10 is characterized by a sharp metamagnetic transition and
ferromagnetic behavior occurring within the basal plane and along the c-axis,
respectively. Resistivity at magnetic field, B, exhibits low-frequency quantum
oscillations when B||c-axis and large magnetoresistivity accompanied by
critical fluctuations driven by the metamagnetism when B^c-axis. The complex
behavior evidenced in resistivity, magnetization and specific heat presented is
not characteristic of any obvious ground states, and points to an exotic state
that shows a delicate balance between fluctuations and order.Comment: 18 pages, 4 figure
Destruction of the Mott Insulating Ground State of Ca_2RuO_4 by a Structural Transition
We report a first-order phase transition at T_M=357 K in single crystal
Ca_2RuO_4, an isomorph to the superconductor Sr_2RuO_4. The discontinuous
decrease in electrical resistivity signals the near destruction of the Mott
insulating phase and is triggered by a structural transition from the low
temperature orthorhombic to a high temperature tetragonal phase. The magnetic
susceptibility, which is temperature dependent but not Curie-like decreases
abruptly at TM and becomes less temperature dependent. Unlike most insulator to
metal transitions, the system is not magnetically ordered in either phase,
though the Mott insulator phase is antiferromagnetic below T_N=110 K.Comment: Accepted for publication in Phys. Rev. B (Rapid Communications
Control of lasing in fully chaotic open microcavities by tailoring the shape factor
We demonstrate experimentally that lasing in a semiconductor microstadium can
be optimized by controlling its shape. Under spatially uniform optical pumping,
the first lasing mode in a GaAs microstadium with large major-to-minor-axis
ratio usually corresponds to a high-quality scar mode consisting of several
unstable periodic orbits. Interference of waves propagating along the
constituent orbits may minimize light leakage at particular major-to-minor-axis
ratio. By making stadium of the optimum shape, we are able to maximize the mode
quality factor and align the mode frequency to the peak of the gain spectrum,
thus minimizing the lasing threshold. This work opens the door to control
chaotic microcavity lasers by tailoring the shape factor
Suppression of magnetism in Ba5AlIr2O11: interplay of Hund's coupling, molecular orbitals and spin-orbit interaction
The electronic and magnetic properties of BaAlIrO containing
Ir-Ir dimers are investigated using the GGA and GGA+SOC calculations. We found
that strong suppression of the magnetic moment in this compound recently found
in [J. Terzic {\it et al.}, Phys. Rev. B {\bf 91}, 235147 (2015)] is not due to
charge-ordering, but is related to the joint effect of the spin-orbit
interaction and strong covalency, resulting in the formation of metal-metal
bonds. They conspire and act against the intra-atomic Hund's rule exchange
interaction to reduce total magnetic moment of the dimer. We argue that the
same mechanism could be relevant for other and dimerized transition
metal compounds
Medium polarization in asymmetric nuclear matter
The influence of the core polarization on the effective nuclear interaction
of asymmetric nuclear matter is calculated in the framework of the induced
interaction theory. The strong isospin dependence of the density and spin
density fluctuations is studied along with the interplay between the neutron
and proton core polarizations. Moving from symmetric nuclear matter to pure
neutron matter the crossover of the induced interaction from attractive to
repulsive in the spin singlet state is determined as a function of the isospin
imbalance.The density range in which it occurs is also determined. For the spin
triplet state the induced interaction turns out to be always repulsive. The
implications of the results for the neutron star superfluid phases are shortly
discussed.Comment: 6 pages, 4 figure
Evolution of Magnetism in Single-Crystal Honeycomb Iridates
We report the successful synthesis of single-crystals of the layered iridate,
(NaLi)IrO, , and a thorough study of
its structural, magnetic, thermal and transport properties. The new compound
allows a controlled interpolation between NaIrO and LiIrO,
while maintaing the novel quantum magnetism of the honeycomb Ir planes.
The measured phase diagram demonstrates a dramatic suppression of the N\'eel
temperature, , at intermediate suggesting that the magnetic order in
NaIrO and LiIrO are distinct, and that at , the
compound is close to a magnetically disordered phase that has been sought after
in NaIrO and LiIrO. By analyzing our magnetic data with a
simple theoretical model we also show that the trigonal splitting, on the
Ir ions changes sign from NaIrO and LiIrO, and the
honeycomb iridates are in the strong spin-orbit coupling regime, controlled by
\jeff=1/2 moments.Comment: updated version with more dat
Single Top Quark Production and Decay at Next-to-leading Order in Hadron Collision
We present a calculation of the next-to-leading order QCD corrections, with
one-scale phase space slicing method, to single top quark production and decay
process at hadron colliders.
Using the helicity amplitude method, the angular correlation of the final state
partons and the spin correlation of the top quark are preserved. The effect of
the top quark width is also examined.Comment: 47 pages, 9 figure
- …