1,721,110 research outputs found
Tunable electronic and magnetic phases in layered ruthenates: SrRuO3-SrTiO3 heterostructure upon strain
Full text linkLayered ruthenates are a unique class of systems which manifests a variety of
electronic and magnetic features emerged from competing energy scales. At the
heart of such features lies the multi-orbital physics, especially, the
orbital-selective behavior. Here, we propose that the SrRuO3-SrTiO3
heterostructure is a highly tunable platform to obtain the various emergent
properties. Employing the density functional theory plus dynamical mean-field
theory, we thoroughly investigate the orbital-dependent physics of the system
and identify the competing magnetic fluctuations. We show that the epitaxial
strain drives the system towards multi-orbital or orbital selective Mott phases
from the Hund metal regime. At the same time, the two different types of static
magnetism are stabilized, ferromagnetism and checkerboard antiferromagnetism,
from the competition with the spin-density wave instability.Comment: 5 pages, 3 figures in the main text, Supplemental Material is
include
Competing spin-fluctuations in SrRuO and their tuning through epitaxial strain
Full text linkIn this study, we report the magnetic energy landscape of Sr2RuO4 employing
the generalized Bloch approach within density functional theory. We identify
the two dominant magnetic instabilities, ferromagnetic and spin-density-wave,
together with other predominant instabilities. We show that epitaxial strain
can change the overall magnetic tendency of the system, and tune the relative
weight of the various magnetic instabilities in the system. Especially, the
balance between spin-density wave and ferromagnetic instabilities can be
controlled by the strain, and, eventually can lead to the new magnetic phases
as well as superconducting phases with possibly altered pairing channels. Our
findings are compared with previous theoretical models and experimental reports
for the various magnetic features of the system and offer a first-principles
explanation to them
Correlated insulator collapse due to quantum avalanche via in-gap ladder states
No full textThe significant discrepancy observed between the predicted and experimental switching fields in correlated insulators under a DC electric field far-from-equilibrium necessitates a reevaluation of current microscopic understanding. Here we show that an electron avalanche can occur in the bulk limit of such insulators at arbitrarily small electric field by introducing a generic model of electrons coupled to an inelastic medium of phonons. The quantum avalanche arises by the generation of a ladder of in-gap states, created by a multi-phonon emission process. Hot-phonons in the avalanche trigger a premature and partial collapse of the correlated gap. The phonon spectrum dictates the existence of two-stage versus single-stage switching events which we associate with charge-density-wave and Mott resistive phase transitions, respectively. The behavior of electron and phonon temperatures, as well as the temperature dependence of the threshold fields, demonstrates how a crossover between the thermal and quantum switching scenarios emerges within a unified framework of the quantum avalanche. © 2023, The Author(s).11Nsciescopu
Role of generic scale invariance in a Mott transition from a U(1) spin-liquid insulator to a Landau Fermi-liquid metal
No full textWe investigate the role of generic scale invariance in a Mott transition from a U(1) spin-liquid insulator to a Landau Fermi-liquid metal, where there exist massless degrees of freedom in addition to quantum critical fluctuations. Here, the Mott quantum criticality is described by critical charge fluctuations, and additional gapless excitations are U(1) gauge-field fluctuations coupled to a spinon Fermi surface in the spin-liquid state, which turn out to play a central role in the Mott transition. An interesting feature of this problem is that the scaling dimension of effective leading local interactions between critical charge fluctuations differs from that of the coupling constant between U(1) gauge fields and matter-field fluctuations in the presence of a Fermi surface. As a result, there appear dangerously irrelevant operators, which can cause conceptual difficulty in the implementation of renormalization group (RG) transformations. Indeed, we find that the curvature term along the angular direction of the spinon Fermi surface is dangerously irrelevant at this spin-liquid Mott quantum criticality, responsible for divergence of the self-energy correction term in U(1) gauge-field fluctuations. Performing the RG analysis in the one-loop level based on the dimensional regularization method, we reveal that such extremely overdamped dynamics of U(1) gauge-field fluctuations, which originates from the emergent one-dimensional dynamics of spinons, does not cause any renormalization effects to the effective dynamics of both critical charge fluctuations and spinon excitations. How-ever, it turns out that the coupling between U(1) gauge-field fluctuations and both matter-field excitations still persists at this Mott transition, which results in novel mean-field dynamics to explain the nature of the spin-liquid Mott quantum criticality. We discuss physical implications of effective one-dimensional spin dynamics and extremely overdamped gauge dynamics at the Mott quantum criticality. (c) 2021 Elsevier Inc. All rights reserved.11Nsciescopu
Weak-coupling to strong-coupling quantum criticality crossover in a Kitaev quantum spin liquid -RuCl
No full textWe report an unprecedented quantum criticality crossover representing two
different universal scaling behaviors in a Kitaev quantum magnetic material
-RuCl. -RuCl presents both a symmetry breaking
antiferromagnetic order and a long-range entangled topological order of a
quantum spin liquid, and thus could be a candidate system for a new
universality class involving deconfined fractionalized excitations of the local
Z fluxes and itinerant Majorana fermions. Theoretical analyses on the
inelastic neutron scattering and specific heat results demonstrate that
Wilson-Fisher-Yukawa-type 'conventional' weak-coupling quantum criticality in
high energy scales crosses over to heavy-fermion-type 'local' strong-coupling
one in low energy scales. Our findings provide deep insight on how the quantum
criticality evolves in fermion-boson coupled topological systems with different
types of deconfined fermions.Comment: 14 pages, 11 figure
Classification of multiple arbitrary-order non-Hermitian singularities
Full text linkWe demonstrate general classifications of Riemann surface topology generated
by multiple arbitrary-order exceptional points of quasi-stationary states. Our
studies reveal all possible product permutations of holonomy matrices that
describe a stroboscopic encircling of 2nd order exceptional points. The
permutations turn out to be categorized into a finite number of classes
according to the topological structures of the Riemann surfaces. We further
show that the permutation classes can be derived from combinations of cyclic
building blocks associated with higher-order exceptional points. Our results
are verified by an effective non-Hermitian Hamiltonian founded on generic
Jordan forms and then examined in physical systems of desymmetrized optical
microcavities
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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