Magnetic properties of frustrated two-dimensional<i>S</i>= 1/2 antiferromagnets on a square lattice

Carretta, P.; Papinutto, N.; Melzi, Roberto; Millet, P.; Gonthier, S.; Mendels, P.; Wzietek, P.

doi:10.1088/0953-8984/16/11/040

Cited by 14 publications

(25 citation statements)

References 27 publications

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“…The discovery of two classes of layered vanadium oxides Li 2 VOXO 4 (X = Si, Ge) [137][138][139][140] and AA'VO(PO 4 ) 2 (A, A = Pb, Zn, Sr, Ba) [5,100,101,141,142] provided a variable platform of 2D frustrated quantum magnets with different chemical composition. Nevertheless their magnetism is described universally by the J 1 -J 2 model with J 2 /J 1 or φ depending on the specific compound.…”

Section: The Layered Vanadium Oxides: Magnetization and Susceptibilitymentioning

confidence: 99%

Frustrated two dimensional quantum magnets

Schmidt¹,

Thalmeier²

2017

Physics Reports

105

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We overview physical effects of exchange frustration and quantum spin fluctuations in (quasi-) two dimensional (2D) quantum magnets (S = 1/2) with square, rectangular and triangular structure. Our discussion is based on the J(1)-J(2) type frustrated exchange model and its generalizations. These models are closely related and allow to tune between different phases, magnetically ordered as well as more exotic nonmagnetic quantum phases by changing only one or two control parameters. We survey ground state properties like magnetization, saturation fields, ordered moment and structure factor in the full phase diagram as obtained from numerical exact diagonalization computations and analytical linear spin wave theory. We also review finite temperature properties like susceptibility, specific heat and magnetocaloric effect using the finite temperature Lanczos method. This method is powerful to determine the exchange parameters and g-factors from experimental results. We focus mostly on the observable physical frustration effects in magnetic phases where plenty of quasi-2D material examples exist to identify the influence of quantum fluctuations on magnetism. (C) 2017 Elsevier B.V. All rights reserved

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Section: The Layered Vanadium Oxides: Magnetization and Susceptibilitymentioning

confidence: 99%

Frustrated two dimensional quantum magnets

Schmidt¹,

Thalmeier²

2017

Physics Reports

105

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“…5), with a slope given by the hyperfine coupling. Remarkably, for T c < T < J 1 + J 2 a change in the slope of 7 Li K vs χ s is noticed [22], suggesting a modification in the average hyperfine coupling (see Sect. I).…”

Section: Antiferromagnets On a Square-lattice With Competing Interactmentioning

confidence: 90%

NMR and µSR in Highly Frustrated Magnets

Carretta

Keren

2010

Introduction to Frustrated Magnetism

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Hereafter we shall present a brief overview on some of the most significant achievements obtained by means of NMR and µSR techniques in highly frustrated magnets. First the basic quantities measured by the two techniques will be presented and their connection to the microscopic static and dynamical spin susceptibility recalled. Then the main findings will be outlined, starting from the most simple frustrated units, the molecular nanomagnets, to artificially built frustrated systems as 3 He on graphite, to magnets with a macroscopically degenerate ground-state as the ones on a pyrochlore or kagomé lattices.1 Some basic aspects of NMR and µSR techniques NMR and µSR are very powerful techniques which allow to investigate the microscopic properties of spin systems through the study of the time evolution of the nuclear magnetization M (t) and of the muon spin polarization P (t), respectively [1,2]. Each technique has its advantages and disadvantages. In NMR one knows the crystallographic position of the nuclei under investigation and, therefore NMR results can be more suitably compared to theories. On the other hand, NMR experiments cannot be performed in compounds where just low sensitivity nuclei are present or where the fast nuclear relaxations prevent the observation of an NMR signal. Still, polarized muons can be injected into the sample and used as a probe of the local microscopic properties of the system under investigation. Moreover, by means of µSR it is possible to detect relaxation times shorter than 0.1 µs, about two order of magnitudes shorter than the shortest relaxation time NMR can measure. Since the nuclear magnetization is the quantity detected in the NMR experiments, generally a magnetic field has to be applied to generate it. On the other hand, the muon beam is already polarized before entering the sample, so that the system under investigation can also be studied in zero field by means of µSR. This aspect is particularly relevant if one wants to investigate the intrinsic properties of a certain system without perturbing it with a magnetic field. Nevertheless,

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“…The discovery of two classes of layered vanadium oxides Li 2 VOXO 4 (X = Si, Ge) 4,5,50,51 and AA VO(PO 4 ) 2 (A, A = Pb, Zn, Sr, Ba) 6,7,49,52 provided a variable platform of 2D frustrated quantum magnets with different chemical composition. Nevertheless their magnetism is described universally by the J 1 -J 2 model with J 2 /J 1 or φ depending on the specific compound.…”

Section: Application To Quasi-2d Oxovanadate Compoundsmentioning

confidence: 99%

“…However in reality these magnets nevertheless mostly exhibit long range magnetic order at even lower temperature. This is due to their quasi-2D character caused by the finite inter-plane interactions J ⊥ J c in real compounds such as the S = 1/2 layered vanadium compounds [4][5][6][7] listed in Table II. A famous example is La 2 CuO 4 , the antiferromagnetic parent compound of high-T c superconductors. Although the interplane coupling is extremely small J ⊥ /J c ≈ 1.3 · 10 −6 a large Néel temperature T N = 325 K is observed 8 .…”

Section: Introductionmentioning

confidence: 99%

Néel temperature and reentrant H−T phase diagram of quasi-two-dimensional frustrated magnets

Schmidt

Thalmeier

2017

Phys. Rev. B

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In quasi-2D quantum magnets the ratio of Néel temperature T N to Curie-Weiss temperature Θ CW is frequently used as an empirical criterion to judge the strength of frustration. In this work we investigate how these quantities are related in the canonical quasi-2D frustrated square or triangular J 1 -J 2 model. Using the self-consistent Tyablikov approach for calculating T N we show their dependence on the frustration control parameter J 2 /J 1 in the whole Néel and columnar antiferromagnetic phase region. We also discuss approximate analytical results. In addition the field dependence of T N (H) and the associated possible reentrance behavior of the ordered moment due to quantum fluctuations is investigated. These results are directly applicable to a class of quasi-2D oxovanadate antiferromagnets. We give clear criteria to judge under which conditions the empirical frustration ratio f = Θ CW /T N may be used as measure of frustration strength in the quasi-2D quantum magnets.

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Magnetic properties of frustrated two-dimensionalS= 1/2 antiferromagnets on a square lattice

Cited by 14 publications

References 27 publications

Frustrated two dimensional quantum magnets

Frustrated two dimensional quantum magnets

NMR and µSR in Highly Frustrated Magnets

Néel temperature and reentrant H−T phase diagram of quasi-two-dimensional frustrated magnets

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