201 research outputs found
Robust charge and magnetic order under electric field and current in the multiferroic LuFe(2)O(4)
We performed elastic neutron scattering measurements on the charge- and
magnetically-ordered multiferroic material LuFe(2)O(4). An external electric
field along the [001] direction with strength up to 20 kV/cm applied at low
temperature (~100 K) does not affect either the charge or magnetic structure.
At higher temperatures (~360 K), before the transition to three-dimensional
charge-ordered state, the resistivity of the sample is low, and an electric
current was applied instead. A reduction of the charge and magnetic peak
intensities occurs when the sample is cooled under a constant electric current.
However, after calibrating the real sample temperature using its own
resistance-temperature curve, we show that the actual sample temperature is
higher than the thermometer readings, and the "intensity reduction" is entirely
due to internal sample heating by the applied current. Our results suggest that
the charge and magnetic orders in LuFe(2)O(4) are unaffected by the application
of external electric field/current, and previously observed electric
field/current effects can be naturally explained by internal sample heating.Comment: Version as appeared in PRB
Cu nuclear magnetic resonance study of charge and spin stripe order in LaBaCuO
We present a Cu nuclear magnetic/quadrupole resonance study of the charge
stripe ordered phase of LBCO, with detection of previously unobserved
('wiped-out') signal. We show that spin-spin and spin-lattice relaxation rates
are strongly enhanced in the charge ordered phase, explaining the apparent
signal decrease in earlier investigations. The enhancement is caused by
magnetic, rather than charge fluctuations, conclusively confirming the
long-suspected assumption that spin fluctuations are responsible for the
wipeout effect. Observation of the full Cu signal enables insight into the spin
and charge dynamics of the stripe-ordered phase, and measurements in external
magnetic fields provide information on the nature and suppression of spin
fluctuations associated with charge order. We find glassy spin dynamics, in
agreement with previous work, and incommensurate static charge order with
charge modulation amplitude similar to other cuprate compounds, suggesting that
the amplitude of charge stripes is universal in the cuprates.Comment: 7 pages, 5 figure
Indium substitution effect on the topological crystalline insulator family (PbSn)InTe: Topological and superconducting properties
Topological crystalline insulators (TCIs) have been of great interest in the
area of condensed matter physics. We investigated the effect of indium
substitution on the crystal structure and transport properties in the TCI
system (PbSn)InTe. For samples with a tin
concentration , the low-temperature resisitivities show a dramatic
variation as a function of indium concentration: with up to ~2% indium doping
the samples show weak-metallic behavior, similar to their parent compounds;
with ~6% indium doping, samples have true bulk-insulating resistivity and
present evidence for nontrivial topological surface states; with higher indium
doping levels, superconductivity was observed, with a transition temperature,
Tc, positively correlated to the indium concentration and reaching as high as
4.7 K. We address this issue from the view of bulk electronic structure
modified by the indium-induced impurity level that pins the Fermi level. The
current work summarizes the indium substitution effect on (Pb,Sn)Te, and
discusses the topological and superconducting aspects, which can be provide
guidance for future studies on this and related systems.Comment: 16 pages, 8 figure
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