Quantum Griffiths Phase Inside the Ferromagnetic Phase of 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>Ni</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">V</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:mrow></mml:math>

Wang, Ruizhe; Gebretsadik, Adane; Ubaid-Kassis, Sara; Schroeder, Almut; Vojta, Thomas; Baker, Peter J.; Pratt, F. L.; Blundell, Stephen J.; Lancaster, Tom; Franke, Isabel; Möller, J. S.; Page, Katharine

doi:10.1103/physrevlett.118.267202

Cited by 36 publications

(47 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[8], and for recent experimental observations of GM singularities see Ref. [9]. In the quantum paramagnetic phase in the limit as T → 0 GM singularities are characterized by a dynamical exponent z ′ which varies as the QCP is approached.…”

mentioning

confidence: 98%

Critical and Griffiths-McCoy singularities in quantum Ising spin glasses on d -dimensional hypercubic lattices: A series expansion study

Singh

Young

2017

Phys. Rev. E

View full text Add to dashboard Cite

We study the ±J transverse-field Ising spin glass model at zero temperature on d-dimensional hypercubic lattices and in the Sherrington-Kirkpatrick (SK) model, by series expansions around the strong field limit. In the SK model and in high-dimensions our calculated critical properties are in excellent agreement with the exact mean-field results, surprisingly even down to dimension d = 6 which is below the upper critical dimension of d = 8. In contrast, in lower dimensions we find a rich singular behavior consisting of critical and Griffiths-McCoy singularities. The divergence of the equal-time structure factor allows us to locate the critical coupling where the correlation length diverges, implying the onset of a thermodynamic phase transition. We find that the spin-glass susceptibility as well as various power-moments of the local susceptibility become singular in the paramagnetic phase before the critical point. Griffiths-McCoy singularities are very strong in twodimensions but decrease rapidly as the dimension increases. We present evidence that high enough powers of the local susceptibility may become singular at the pure-system critical point.The combination of quantum mechanics and disorder leads to rich behavior at and near zero temperature quantum critical points (QCPs). For example, the one dimensional random transverse field Ising model has a QCP in which average and typical correlation functions have different critical exponents [1,2], and the time-dependence is described by activated dynamical scaling, in which the log of the relaxation time is proportional to a power of the correlation length ξ, rather than conventional dynamical scaling in which the relaxation time itself is proportional to ξ z , where z is dynamical exponent. Distributions of several quantities are very broad at the quantum critical point (QCP) so QCP's with these features are said to be of the "infinite-randomness" type. It has been proposed [3] that infinite-randomness QCP's can occur in dimension higher than 1. It is also proposed [3] that the infinite-randomness QCP can occur in spin glasses, on the grounds that frustration is irrelevant since the distribution of renormalized interactions (as one perform renormalization group transformations) is so broad that only the largest one matters.In addition, singularities can occur in the paramagnet phase in the region where the corresponding non-random system would be ordered. This was first pointed out for classical systems by Griffiths [4], though the singularities turn out to be unobservably weak in that case [5]. However, these singularities are much stronger in the quantum case, as first shown by McCoy [6,7], and can lead to power-law singularities in local quantities in part of the paramagnetic phase. For quantum problems we will refer to these effects as Griffiths-McCoy (GM) singularities. For a review see Ref. [8], and for recent experimental observations of GM singularities see Ref. [9]. In the quantum paramagnetic phase in the limit as T → 0 GM singularities are characteriz...

show abstract

mentioning

confidence: 98%

Critical and Griffiths-McCoy singularities in quantum Ising spin glasses on d -dimensional hypercubic lattices: A series expansion study

Singh

Young

2017

Phys. Rev. E

View full text Add to dashboard Cite

show abstract

“…As a result, quenchedin chemical disorder between Mn and Fe leads to a continuum of atomic scale AFM-in-FM magnetic orderings over a broad composition interval. This unusual behavior is akin to a Griffiths [13][14][15][16] phase, and is responsible for the anomalous exchange hardening seen in this single-phase material.…”

Section: Introductionmentioning

confidence: 90%

“…Prior work [5,6] has shown that significant chemical disorder is present only on the (Mn,Fe) FCC sub-lattice, and that the moments on the Ru and Sn sites do not contribute meaningfully to the magnetic ordering. The relevant chemical and magnetic configurational degrees of freedom can therefore be restricted to the (Mn,Fe) FCC sub-lattice, while the Ru and Sn sub-lattices are present only during the electronic structure calculations used to generate training data to arXiv:1910.07543v1 [cond-mat.mtrl-sci] 16 Oct 2019 parameterize the chemomagnetic cluster expansion.…”

Section: Theory and Methodsmentioning

confidence: 99%

Modeling magnetic evolution and exchange hardening in disordered magnets: The example of Mn1−xFexRu2Sn Heusler alloys

Decolvenaere

Levin

Seshadri

et al. 2019

Phys. Rev. Materials

View full text Add to dashboard Cite

We demonstrate how exchange hardening can arise in a chemically-disordered solid solution from a first-principles statistical mechanics approach. A general mixed-basis chemical and magnetic cluster expansion has been developed, and applied to the Mn1−xFexRu2Sn Heusler alloy system; single-phase solid solutions between antiferromagnetic MnRu 2 Sn and ferromagnetic FeRu 2 Sn with disorder on the Mn/Fe sublattice that exhibit unexpected exchange hardening. Monte Carlo simulations applied to the cluster expansion are able to reproduce the experimentally measured magnetic transition temperatures and the bulk magnetization as a function of composition. The magnetic ordering around a site is shown to be dependent not only on bulk composition, but also on the identity of the site and the local composition around that site. The simulations predict that local antiferromagnetic orderings form inside a bulk ferromagnetic region at intermediate compositions that drives the exchange hardening. Furthermore, the antiferromagnetic regions disorder at a lower temperature than the ferromagnetic regions, providing an atomistic explanation for the experimentally-observed decrease in exchange hardening with increasing temperature. These effects occur on a length scale too small to be resolved with previously-used characterization techniques.

show abstract

“…This can promote what were weak essential singularities in thermodynamic quantities into power-laws. As a consequence, these quantum Griffiths-McCoy singularities [4,5] are important both for experiments [6] and numerical calculations [7][8][9]. For a more comprehensive discussion on Griffiths-McCoy singularities in a myriad of disordered models and on the role of disorder in general in quantum critical behavior, see [10].…”

Section: Introductionmentioning

confidence: 99%

Griffiths-McCoy singularities in the dilute transverse-field Ising model: A numerical linked cluster expansion study

Thompson

Singh

2019

Phys. Rev. E

View full text Add to dashboard Cite

We use Numerical Linked Cluster Expansions (NLCE) to study the site diluted transverse-field Ising model on the square-lattice at T = 0. NLCE with a self-consistent mean-field on the boundary of the clusters is used to obtain the ground state magnetization, susceptibility, and structure factor as a function of transverse field h and exchange constant J. Adding site-dilution to the model turns NLCE into a series expansion in the dilution parameter p. Studying the divergence of the structure factor allows us to establish the phase-diagram in the h/J and p plane. By studying the magnetization of the system in a longitudinal field, we investigate the Griffiths-McCoy (GM) singularities. We find that the magnetization develops non-linearities in the Griffiths phase with exponents that vary continuously with h. Additionally, the probability distribution of the local susceptibility develops long tails in the Griffith's phase, which is studied in terms of its moments.

show abstract

Quantum Griffiths Phase Inside the Ferromagnetic Phase of Ni1−xVx

Cited by 36 publications

References 45 publications

Critical and Griffiths-McCoy singularities in quantum Ising spin glasses on d -dimensional hypercubic lattices: A series expansion study

Critical and Griffiths-McCoy singularities in quantum Ising spin glasses on d -dimensional hypercubic lattices: A series expansion study

Modeling magnetic evolution and exchange hardening in disordered magnets: The example of Mn1−xFexRu2Sn Heusler alloys

Griffiths-McCoy singularities in the dilute transverse-field Ising model: A numerical linked cluster expansion study

Contact Info

Product

Resources

About