525 research outputs found
Uniform Mixing of High-Tc Superconductivity and Antiferromagnetism on a Single CuO2 Plane in Hg-based Five-layered Cuprate
We report a site selective Cu-NMR study on under-doped Hg-based five-layered
high- cuprate HgBa2Ca4Cu5Oy with a Tc=72 K. Antiferromagnetism (AF)
has been found to take place at TN=290 K, exhibiting a large antiferromagnetic
moment of 0.67-0.69uB at three inner planes (IP's). This value is comparable to
the values reported for non-doped cuprates, suggesting that the IP may be in a
nearly non-doped regime. Most surprisingly, the AF order is also detected with
M(OP)=0.1uB even at two outer planes (OP's) that are responsible for the onset
of superconductivity (SC). The high-Tc SC at Tc = 72 K can uniformly coexist on
a microscopic level with the AF at OP's. This is the first microscopic evidence
for the uniform mixed phase of AF and SC on a single CuO2 plane in a simple
environment without any vortex lattice and/or stripe order.Comment: 4 pages, 4 figures. To be published in Phys.Rev.Let
Unique phase diagram with narrow superconducting dome in EuFe(AsP) due to Eu local magnetic moments
The interplay between superconductivity and Eu magnetic moments in
EuFe(AsP) is studied by electrical resistivity measurements
under hydrostatic pressure on and single crystals. We can map
hydrostatic pressure to chemical pressure and show, that superconductivity
is confined to a very narrow range in the phase diagram,
beyond which ferromagnetic (FM) Eu ordering suppresses superconductivity. The
change from antiferro- to FM Eu ordering at the latter concentration coincides
with a Lifshitz transition and the complete depression of iron magnetic order.Comment: 4 page
Experimental Quantification of Entanglement Through Heat Capacity
A new experimental realization of heat capacity as an entanglement witness
(EW) is reported. Entanglement properties of a low dimensional quantum spin
system are investigated by heat capacity measurements performed down to very
low temperatures (400mK), for various applied magnetic field values. The
experimentally extracted results for the value of heat capacity at zero field
matches perfectly with the theoretical estimates of entanglement from model
Hamiltonians. The studied sample is a spin antiferromagnetic
system which shows clear signature of quantum phase transition (QPT) at very
low temperatures when the heat capacity is varied as a function of fields at a
fixed temperature. The variation of entanglement as a function of field is then
explored in the vicinity of the quantum phase transition to capture the sudden
loss of entanglement.Comment: 8 pages, 6 figures, To be published in NJ
Magnetic phase transitions in the two-dimensional frustrated quantum antiferromagnet Cs2CuCl4
We report magnetization and specific heat measurements in the 2D frustrated
spin-1/2 Heisenberg antiferromagnet Cs2CuCl4 at temperatures down to 0.05 K and
high magnetic fields up to 11.5 T applied along a, b and c-axes. The low-field
susceptibility chi (T) M/B shows a broad maximum around 2.8 K characteristic of
short-range antiferromagnetic correlations and the overall temperature
dependence is well described by high temperature series expansion calculations
for the partially frustrated triangular lattice with J=4.46 K and J'/J=1/3. At
much lower temperatures (< 0.4 K) and in in-plane field (along b and c-axes)
several new intermediate-field ordered phases are observed in-between the
low-field incommensurate spiral and the high-field saturated ferromagnetic
state. The ground state energy extracted from the magnetization curve shows
strong zero-point quantum fluctuations in the ground state at low and
intermediate fields
Coexistence of Superconductivity and Antiferromagnetism in Multilayered High- Superconductor HgBaCaCuO: A Cu-NMR Study
We report a coexistence of superconductivity and antiferromagnetism in
five-layered compound HgBaCaCuO (Hg-1245) with K,
which is composed of two types of CuO planes in a unit cell; three inner
planes (IP's) and two outer planes (OP's). The Cu-NMR study has revealed that
the optimallydoped OP undergoes a superconducting (SC) transition at
K, whereas the three underdoped IP's do an antiferromagnetic (AF) transition
below 60 K with the Cu moments of . Thus bulk
superconductivity with a high value of K and a static AF ordering at
K are realized in the alternating AF and SC layers. The AF-spin
polarization at the IP is found to induce the Cu moments of at
the SC OP, which is the AF proximity effect into the SC OP.Comment: 6 pages, 8 figure
Tuning of magnetic quantum criticality in artificial Kondo superlattice CeRhIn5/YbRhIn5
The effects of reduced dimensions and the interfaces on antiferromagnetic
quantum criticality are studied in epitaxial Kondo superlattices, with
alternating layers of heavy-fermion antiferromagnet CeRhIn and 7 layers
of normal metal YbRhIn. As is reduced, the Kondo coherence temperature
is suppressed due to the reduction of effective Kondo screening. The N\'{e}el
temperature is gradually suppressed as decreases and the quasiparticle mass
is strongly enhanced, implying dimensional control toward quantum criticality.
Magnetotransport measurements reveal that a quantum critical point is reached
for superlattice by applying small magnetic fields. Remarkably, the
anisotropy of the quantum critical field is opposite to the expectations from
the magnetic susceptibility in bulk CeRhIn, suggesting that the Rashba
spin-orbit interaction arising from the inversion symmetry breaking at the
interface plays a key role for tuning the quantum criticality in the
two-dimensional Kondo lattice.Comment: Main text: 5 pages, 4 figures; Supplemental material:6 pages, 3
figures. Accepted for publication in Physical Review Letter
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