70 research outputs found
Low temperature magnetic structure of CeRhIn by neutron diffraction on absorption-optimized samples
Two aspects of the ambient pressure magnetic structure of heavy fermion
material CeRhIn have remained under some debate since its discovery:
whether the structure is indeed an incommensurate helix or a spin density wave,
and what is the precise magnitude of the ordered magnetic moment. By using a
single crystal sample optimized for hot neutrons to minimize neutron absorption
by Rh and In, here we report an ordered moment of . In
addition, by using spherical neutron polarimetry measurements on a similar
single crystal sample, we have confirmed the helical nature of the magnetic
structure, and identified a single chiral domain
Competing magnetic fluctuations in Sr3Ru2O7 probed by Ti doping
We report the effect of nonmagnetic Ti4+ impurities on the electronic and
magnetic properties of Sr3Ru2O7. Small amounts of Ti suppress the
characteristic peak in magnetic susceptibility near 16 K and result in a sharp
upturn in specific heat. The metamagnetic quantum phase transition and related
anomalous features are quickly smeared out by small amounts of Ti. These
results provide strong evidence for the existence of competing magnetic
fluctuations in the ground state of Sr3Ru2O7. Ti doping suppresses the low
temperature antiferromagnetic interactions that arise from Fermi surface
nesting, leaving the system in a state dominated by ferromagnetic fluctuations.Comment: 5 pages, 4 figures, 1 tabl
Charge carrier localization induced by excess Fe in the Fe1+y(Te,Se) superconductor system
We have investigated the effect of Fe nonstoichiometry on properties of the
Fe1+y(Te, Se) superconductor system by means of resistivity, Hall coefficient,
magnetic susceptibility, and specific heat measurements. We find that the
excess Fe at interstitial sites of the (Te, Se) layers not only suppresses
superconductivity, but also results in a weakly localized electronic state. We
argue that these effects originate from the magnetic coupling between the
excess Fe and the adjacent Fe square planar sheets, which favors a short-range
magnetic order.Comment: 15 pages, 6 figures accepted for publication in PR
A microscopic Kondo lattice model for the heavy fermion antiferromagnet CeIn
Electrons at the border of localization generate exotic states of matter
across all classes of strongly correlated electron materials and many other
quantum materials with emergent functionality. Heavy electron metals are a
model example, in which magnetic interactions arise from the opposing limits of
localized and itinerant electrons. This remarkable duality is intimately
related to the emergence of a plethora of novel quantum matter states such as
unconventional superconductivity, electronic-nematic states, hidden order and
most recently topological states of matter such as topological Kondo insulators
and Kondo semimetals and putative chiral superconductors. The outstanding
challenge is that the archetypal Kondo lattice model that captures the
underlying electronic dichotomy is notoriously difficult to solve for real
materials. Here we show, using the prototypical strongly-correlated
antiferromagnet CeIn, that a multi-orbital periodic Anderson model embedded
with input from ab initio bandstructure calculations can be reduced to a simple
Kondo-Heisenberg model, which captures the magnetic interactions
quantitatively. We validate this tractable Hamiltonian via high-resolution
neutron spectroscopy that reproduces accurately the magnetic soft modes in
CeIn, which are believed to mediate unconventional superconductivity. Our
study paves the way for a quantitative understanding of metallic quantum states
such as unconventional superconductivity
A microscopic Kondo lattice model for the heavy fermion antiferromagnet CeIn
Electrons at the border of localization generate exotic states of matter across all classes of strongly correlated electron materials and many other quantum materials with emergent functionality. Heavy electron metals are a model example, in which magnetic interactions arise from the opposing limits of localized and itinerant electrons. This remarkable duality is intimately related to the emergence of a plethora of novel quantum matter states such as unconventional superconductivity, electronic-nematic states, hidden order and most recently topological states of matter such as topological Kondo insulators and Kondo semimetals and putative chiral superconductors. The outstanding challenge is that the archetypal Kondo lattice model that captures the underlying electronic dichotomy is notoriously difficult to solve for real materials. Here we show, using the prototypical strongly-correlated antiferromagnet CeIn, that a multi-orbital periodic Anderson model embedded with input from ab initio bandstructure calculations can be reduced to a simple Kondo-Heisenberg model, which captures the magnetic interactions quantitatively. We validate this tractable Hamiltonian via high-resolution neutron spectroscopy that reproduces accurately the magnetic soft modes in CeIn, which are believed to mediate unconventional superconductivity. Our study paves the way for a quantitative understanding of metallic quantum states such as unconventional superconductivity
- …