Strong-disorder magnetic quantum phase transitions: Status and new developments

Vojta, Thomas

doi:10.1088/1742-6596/529/1/012016

Cited by 6 publications

(5 citation statements)

References 55 publications

(69 reference statements)

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“…In solid solutions of the type Ba1-xSrxRuO3, when increasing the values of x, the nine-layer structure with stacking sequence (chh)3 (9R) transforms to the four-layer structure (ch)2 (4H) and finally to the classical perovskite type structure (c)3 (3C) at x is about 1/6 and 1/3, respectively 33 . The 4H and 9R forms of BaRuO3 have substantially different electronic properties 35 , and even the Sr1-xCaxRuO3 perovskites in the more familiar cubic perovskite structure types are famously enigmatic quantum materials [36][37][38] . In the event that readers are not familiar with magnetism we point out that the A ions in perovskites, with the exceptions of the rare earths, are not magnetic (i.e.…”

Section: Mixtures Of Cubic Plus Hexagonal Packingmentioning

confidence: 99%

Hexagonal Perovskites as Quantum Materials

Nguyen

Cava

2020

Chem. Rev.

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Hexagonal oxide perovskites, in contrast to the more familiar perovskites, allow for face-sharing of metal-oxygen octahedra or trigonal prisms within their structural frameworks. This results in dimers, trimers, tetramers, or longer fragments of chains of face-sharing octahedra in the crystal structures, and consequently in much shorter metal-metal distances and lower metal-oxygen-metal bond angles than are seen in the more familiar perovskites. The presence of the face-sharing octahedra can have a dramatic impact on magnetic properties of these compounds, and dimer-based materials, in particular, have been the subjects of many quantum-materials-directed studies in materials physics. Hexagonal oxide perovskites are of contemporary interest due to their potential for geometrical frustration of the ordering of magnetic moments or orbital occupancies at low temperatures, which is especially relevant to their significance as quantum materials. As such, several hexagonal oxide perovskites have been identified as potential candidates for hosting the quantum spin liquid state at low temperatures. In our view, hexagonal oxide perovskites are fertile ground for finding new quantum materials. This review briefly describes the solid state chemistry of many of these materials.

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Section: Mixtures Of Cubic Plus Hexagonal Packingmentioning

confidence: 99%

Hexagonal Perovskites as Quantum Materials

Nguyen

Cava

2020

Chem. Rev.

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“…Parts of this topic have been reviewed recently in Refs. (18,19,78,79). We therefore only summarize the key concepts and emphasize the refined classification developed in Ref.…”

Section: Disordered Phase Transitionsmentioning

confidence: 99%

“…Several other examples of magnetic quantum Griffiths phases in metallic systems have been found in recent years (see Refs. (19,79) and references therein). In 2015, Xing et al (133) reported Griffiths singularities near the superconductor-metal transition in Ga thin films.…”

Section: (A) (B)mentioning

confidence: 99%

Disorder in Quantum Many-Body Systems

Vojta

2019

Annu. Rev. Condens. Matter Phys.

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Impurities, defects, and other types of imperfections are ubiquitous in realistic quantum many-body systems and essentially unavoidable in solid state materials. Often, such random disorder is viewed purely negatively as it is believed to prevent interesting new quantum states of matter from forming and to smear out sharp features associated with the phase transitions between them. However, disorder is also responsible for a variety of interesting novel phenomena that do not have clean counterparts. These include Anderson localization of single particle wave functions, many-body localization in isolated many-body systems, exotic quantum critical points, and "glassy" ground state phases. This brief review focuses on two separate but related subtopics in this field. First, we review under what conditions different types of randomness affect the stability of symmetry-broken low-temperature phases in quantum many-body systems and the stability of the corresponding phase transitions. Second, we discuss the fate of quantum phase transitions that are destabilized by disorder as well as the unconventional quantum Griffiths phases that emerge in their vicinity.

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“…The effects of disorder and/or impurities have been considered as well, unveiling quite a rich phenomenology that ranges from the so-called Griffiths-McCoy singularities [49] to the rounding of a quantum phase transition [50] (for an up-to-date review of theoretical and experimental aspects, see Ref. [51]). …”

Section: Introductionmentioning

confidence: 99%

Universal scaling for the quantum Ising chain with a classical impurity

Apollaro¹,

Francica²,

Giuliano³

et al. 2017

Phys. Rev. B

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We study finite-size scaling for the magnetic observables of an impurity residing at the end point of an open quantum Ising chain with transverse magnetic field, realized by locally rescaling the field by a factor μ = 1. In the homogeneous chain limit at μ = 1, we find the expected finite-size scaling for the longitudinal impurity magnetization, with no specific scaling for the transverse magnetization. At variance, in the classical impurity limit μ = 0, we recover finite scaling for the longitudinal magnetization, while the transverse one basically does not scale. We provide both analytic approximate expressions for the magnetization and the susceptibility as well as numerical evidences for the scaling behavior. At intermediate values of μ, finite-size scaling is violated, and we provide a possible explanation of this result in terms of the appearance of a second, impurity-related length scale. Finally, by going along the standard quantum-to-classical mapping between statistical models, we derive the classical counterpart of the quantum Ising chain with an end-point impurity as a classical Ising model on a square lattice wrapped on a half-infinite cylinder, with the links along the first circle modified as a function of μ.

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Strong-disorder magnetic quantum phase transitions: Status and new developments

Cited by 6 publications

References 55 publications

Hexagonal Perovskites as Quantum Materials

Hexagonal Perovskites as Quantum Materials

Disorder in Quantum Many-Body Systems

Universal scaling for the quantum Ising chain with a classical impurity

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