3,888 research outputs found
Isospin effect on nuclear stopping in intermediate energy Heavy Ion Collisions
By using the Isospin Dependent Quantum Molecular Dynamics Model (IQMD), we
study the dependence of nuclear stopping Q_{ZZ}/A and R in intermediate energy
heavy ion collisions on system size, initial N/Z, isospin symmetry potential
and the medium correction of two-body cross sections. We find the effect of
initial N/Z ratio, isospin symmetry potential on stopping is weak. The
excitation function of Q_{ZZ}/A and R depends on the form of medium correction
of two-body cross sections, the equation of state of nuclear matter (EOS). Our
results show the behavior of the excitation function of Q_{ZZ}/A and R can
provide clearer information of the isospin dependence of the medium correction
of two-body cross sections.Comment: 3 pages including 4 figure
Transport theory in non-Hermitian systems
Non-Hermitian systems have garnered significant attention due to the
emergence of novel topology of complex spectra and skin modes. However,
investigating transport phenomena in such systems faces obstacles stemming from
the non-unitary nature of time evolution. Here, we establish the continuity
equation for a general non-Hermitian Hamiltonian in the Schr\"odinger picture.
It attributes the universal non-conservativity to the anti-commutation
relationship between particle number and non-Hermitian terms. Our work derives
a comprehensive current formula for non-Hermitian systems using Green's
function, applicable to both time-dependent and steady-state responses. To
demonstrate the validity of our approach, we calculate the local current in
models with one-dimensional and two-dimensional settings, incorporating
scattering potentials. The spatial distribution of local current highlights the
widespread non-Hermitian phenomena, including skin modes, non-reciprocal
quantum dots, and corner states. Our findings offer valuable insights for
advancing theoretical and experimental research in the transport of
non-Hermitian systems
Spin-flip reflection at the normal metal-spin superconductor interface
We study spin transport through a normal metal-spin superconductor junction.
A spin-flip reflection is demonstrated at the interface, where a spin-up
electron incident from the normal metal can be reflected as a spin-down
electron and the spin will be injected into the spin
superconductor. When the (spin) voltage is smaller than the gap of the spin
superconductor, the spin-flip reflection determines the transport properties of
the junction. We consider both graphene-based (linear-dispersion-relation) and
quadratic-dispersion-relation normal metal-spin superconductor junctions in
detail. For the two-dimensional graphene-based junction, the spin-flip
reflected electron can be along the specular direction (retro-direction) when
the incident and reflected electron locates in the same band (different bands).
A perfect spin-flip reflection can occur when the incident electron is normal
to the interface, and the reflection coefficient is slightly suppressed for the
oblique incident case. As a comparison, for the one-dimensional
quadratic-dispersion-relation junction, the spin-flip reflection coefficient
can reach 1 at certain incident energies. In addition, both the charge current
and the spin current under a charge (spin) voltage are studied. The spin
conductance is proportional to the spin-flip reflection coefficient when the
spin voltage is less than the gap of the spin superconductor. These results
will help us get a better understanding of spin transport through the normal
metal-spin superconductor junction.Comment: 11 pages, 9 figure
Superconducting state in the non-centrosymmetric Mg_{9.3}Ir_{19}B_{16.7} and Mg_{10.5}Ir_{19}B_{17.1} revealed by NMR
We report ^{11}B NMR measurements in non-centrosymmetric superconductors
Mg_{9.3}Ir_{19}B_{16.7} (T_c=5.8 K) and Mg_{10.5}Ir_{19}B_{17.1} (T_c=4.8 K).
The spin lattice relaxation rate and the Knight shift indicate that the Cooper
pairs are predominantly in the spin-singlet state with an isotropic gap.
However, Mg_{10.5}Ir_{19}B_{17.1} is found to have more defects and the spin
susceptibility remains finite even in the zero-temperature limit. We interpret
this result as that the defects enhance the spin-orbit coupling and bring about
more spin-triplet component.Comment: for a proper, high-resolution Fig.5, contact the corresponding autho
- …