4 research outputs found
Single- and two-particle observables in the Emery model: a dynamical mean-field perspective
We compare the dynamical mean-field descriptions of the single-band Hubbard
model and the three-band Emery model at the one- and two-particle level for
parameters relevant to high-Tc superconductors. We show that even within
dynamical mean-field theory, accounting solely for temporal fluctuations, the
intrinsic multi-orbital nature of the Emery model introduces effective
non-local correlations. These lead to a non-Curie-like temperature-dependence
of the magnetic susceptibility, also seen in nuclear magnetic resonance
experiments in the pseudogap regime by M. Avramovska, et al. [Journal of
Superconductivity and Novel Magnetism 33, 2621 (2020)]. We demonstrate the
agreement of our results with these experiments for a large range of dopings
and trace back the effective non-local correlations to an emerging
oxygen-copper singlet by analyzing a minimal finite-size cluster model. Despite
this correct description of the hallmark of the pseudogap at the two-particle
level, i.e., the drop in the Knight shift of nuclear magnetic resonance,
dynamical mean-field theory fails to properly describe the spectral properties
of the pseudogap.Comment: 7 pages, 7 figure
Metallic islands in the Kondo insulator SmB
The predicted interplay between Kondo physics and non-trivial topology in
SmB has stimulated many experimental reports, some of which are in
apparent contradiction. The origin of the dispute may lie on the fragility of
the Kondo insulating phase in the presence of Sm vacancies (Kondo holes) and/or
natural impurities, such as Gd. In this work, we locally investigated
this fragility for Al-flux grown SmGdB single crystals (0
0.02) by combining electron spin resonance (ESR) and
complementary bulk measurements. The Gd ESR spectra in a highly dilute
regime ( ) display the features of an insulating cubic
environment. Remarkably, a metallic ESR lineshape is observed for more
concentrated samples ( 0.004), even though these systems are still in
a reasonably dilute regime and show insulating electrical resistivity. Our
data indicate that the Kondo insulating state is destroyed locally around
impurities before a global percolation occurs. This result not only explains
the discrepancy between and conductivity, but also provides a
scenario to explain the presence of quantum oscillations in magnetization in
the absence of quantum oscillations in electrical resistivity.Comment: 8 pages, 4 figures, 1 supplementary information. To be published in
Phys. Rev. Researc
Evolution of the magnetic properties in the antiferromagnet Ce<sub>2</sub>RhIn<sub>8</sub> simultaneously doped with Cd and Ir
We report the evolution of the magnetic properties of Ce2Rh1-xIrxIn8-yCdy single crystals. In particular, for Ce2Rh0.5Ir0.5In8 (T-N = 2.0 K) and Ce2Rh0.5Ir0.5In7.79Cd0.21(T-N = 4.2 K), we have solved the magnetic structure of these compounds using single-crystal neutron magnetic diffraction experiments. Taking the magnetic structure of the Ce2RhIn8 heavy-fermion antiferromagnet as a reference, we have identified no changes in the q =(1/2, 1/2, 0) magnetic wave vector; however, the direction of the ordered Ce3+ moments rotates toward the ab plane, under the influence of both dopants. By constraining the analysis of the crystalline electric field (CEF) with the experimental ordered moment's direction and high-temperature magnetic-susceptibility data, we have used a mean-field model with tetragonal CEF and exchange interactions to gain insight into the CEF scheme and anisotropy of the CEF ground-state wave function when Cd and Jr are introduced into Ce2RhIn8. Consistent with previous work, we find that Cd doping in Ce2RhIn8 tends to rotate the magnetic moment toward the ab plane and lower the energy of the CEF excited states' levels. Interestingly, the presence of Jr also rotates the magnetic moment towards the ab plane although its connection to the CEF overall splitting evolution for the y = 0 samples may not be straightforward. These findings may shed light on the origin of the disordered spin-glass phase on the Jr-rich side of the phase diagram and also indicate that the Ce2MIn8 compounds may not follow exactly the same Rh-Ir CEF effects trend established for the CeMIn5 compounds