Dilution-induced order in quasi-one-dimensional quantum antiferromagnets

Shender, E. F.; Kivelson, Steven

doi:10.1103/physrevlett.66.2384

Cited by 60 publications

(47 citation statements)

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“…|M(q)| 2 (integrated) translates directly to the ordered spin moment squared in units of µ B per Cu 2+ . staggered magnetization patterns around each impurity or each vortex, respectively, adjust their individual two-sublattice spin structures in phase and thereby avoid domain walls [31]. For three nearby impurities, however, it already proves difficult to find a specific configuration where anti-phase domain walls are absent.…”

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d-Wave superconductivity as a catalyst for antiferromagnetism in underdoped cuprates

et al. 2010

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Abstract. In underdoped high-T c cuprates, d-wave superconductivity competes with antiferromagnetism. It has generally been accepted that suppressing superconductivity leads to the nucleation of spin-density wave (SDW) order with wavevector near (π, π). We show theoretically, for a d-wave superconductor in an applied magnetic field including disorder and electronic correlations, that the creation of SDW order is in fact not simply due to suppression of superconductivity, but rather due to a correlation-induced splitting of an electronic bound state arising from the sign change of the order parameter along quasiparticle trajectories. The induced SDW order is therefore a direct consequence of the d-wave symmetry. The formation of anti-phase domain walls proves to be crucial for explaining the heretofore puzzling temperature dependence of the induced magnetism as measured by neutron diffraction.A superconductor is characterized by a Bardeen-Cooper-Schrieffer (BCS) order parameter k (R), where R is the center-of-mass coordinate of a Cooper pair of electrons with momenta (k, −k). The bulk ground state of such a system is homogeneous, but a spatial perturbation that breaks pairs, e.g. a magnetic impurity, may cause the suppression of k (R) locally. What is revealed when superconductivity is suppressed is the electronic phase in the absence of k , a normal Fermi liquid. Thus the low-energy excitations near magnetic impurities and in the vortex 4 Author to whom any correspondence should be addressed. [9,10] detected magnetic ordering as a wedge-shaped extension of the 'spin glass' phase into the SC dome of the temperature versus doping phase diagram ( figure 1(a)). Lake et al [2] reported that an incommensurate magnetic order similar to the field-induced state was also observed in zero field. Although it also vanished at T c , the ordered magnetic moment in zero field had a T dependence, which was qualitatively different from the field-induced signal. The zero-field signal was attributed to disorder, but the relation between impurities and magnetic ordering remained unclear. Because strong magnetic fluctuations with similar wavevectors are reported at low but nonzero energies in inelastic neutron scattering experiments on these materials, e.g. on optimally doped LSCO samples exhibiting no spin-glass phase in zero field, it is frequently argued that impurities or vortices simply 'freeze' this fluctuating order [11].Describing such a phenomenon theoretically at the microscopic level is difficult due to the inhomogeneity of the interacting system, but it is important if one wishes to explore situations with strong disorder, where the correlations may no longer reflect the intrinsic spin dynamics of the pure system. Such an approach was proposed in a model calculation for an inhomogeneous d-wave superconductor with Hubbard-type correlations treated in the mean field [12]. In this model, a single impurity creates, at sufficiently large Hubbard interaction U and impurity potential strength V imp , a droplet of staggered magn...

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d-Wave superconductivity as a catalyst for antiferromagnetism in underdoped cuprates

et al. 2010

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“…Perhaps even more surprisingly, doping gapped antiferromagnets with a finite concentration of magnetic or non-magnetic impurities can fill up the bare spin gap with localized levels [11-13] which may eventually order, in the strict sense of macroscopic long-range order (LRO) at low temperature. Such an impurity-induced ordering mechanism of the type "order from disorder" [14,15] [21]. Nevertheless, only a few studies have focused on the effect of an external field [22][23][24][25][26][27].…”

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Disorder-Induced Revival of the Bose-Einstein Condensation inNi(Cl1−xBrx
Dupont
¹
,
Capponi
²
,
Laflorencie
³

2017
Phys. Rev. Lett.
14
5
28
0
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Building on recent NMR experiments [A. Orlova et al., Phys. Rev. Lett. 118, 067203 (2017)], we theoretically investigate the high magnetic field regime of the disordered quasi-one-dimensional S = 1 antiferromagnetic material Ni(Cl1−xBrx)2-4SC(NH2)2. The interplay between disorder, chemically controlled by Br-doping, interactions, and the external magnetic field, leads to a very rich phase diagram. Beyond the well-known antiferromagnetically ordered regime, analog of a Bose condensate of magnons, which disappears when H ≥ 12.3 T, we unveil a resurgence of phase coherence at higher field H ∼ 13.6 T, induced by the doping. Interchain couplings stabilize finite temperature long-range order whose extension in the field -temperature space is governed by the concentration of impurities x. Such a "mini-condensation" contrasts with previously reported Bose-glass physics in the same regime, and should be accessible to experiments.Introduction.-Interacting quantum systems in the presence of disorder have been intensively studied for several decades, leading to fascinating physics, e.g. the Kondo effect [1], the many-body localization transition [2], or the superfluid to Bose-glass (BG) [3,4] transition at finite disorder for lattice bosons [5][6][7]. While counterintuitive, in some situations disorder may enhance long-range order, as discussed for inhomogeneous superconductors [8][9][10]. Perhaps even more surprisingly, doping gapped antiferromagnets with a finite concentration of magnetic or non-magnetic impurities can fill up the bare spin gap with localized levels [11-13] which may eventually order, in the strict sense of macroscopic long-range order (LRO) at low temperature. Such an impurity-induced ordering mechanism of the type "order from disorder" [14,15] [21]. Nevertheless, only a few studies have focused on the effect of an external field [22][23][24][25][26][27].In this Letter, building on recent nuclear magnetic resonance (NMR) experiments [28], we achieve a realistic theoretical study of the high magnetic field regime of Ni(Cl 1−x Br x ) 2 -4SC(NH 2 ) 2 (DTNX): a threedimensional antiferromagnetic (AF) system made of weakly coupled chains of S = 1 spins subject to singleion anisotropy [panels (b-c) of Fig. 1]. Note that the S = 1 chains are not of Haldane type, due to the large anisotropy D [29]. In the absence of chemical disorder (x = 0), NiCl 2 -4SC(NH 2 ) 2 (DTN) provides a very good realization of magnetic field-induced Bose-Einstein condensation (BEC) in a quantum spin system [30][31][32][33] between two critical field H clean

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“…However, the basic physics of ordering is easy to understand. In one dimension Shender and Kivelson [18] pointed out that the interactions between impurities in a quantum spin chain are non-frustrating: if an impurity creates a local AF droplet, a second one can always orient itself to avoid losing exchange energy. In two dimensions (2D) this continues to apply for spin models with nearest neighbor exchange, but may break down in the presence of mobile charges.…”

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“…Fig. 2(a) shows the simplest schematic picture of disorder stabilization of a single Néel phase [18] by nonmagnetic impurities. Not all impurities in the correlated system need "magnetize" for a given U , however: in the disordered system, the effective criterion to drive the impurity through the local magnetic phase transition is different for each impurity.…”

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confidence: 99%

Disorder-Induced Static Antiferromagnetism in Cuprate Superconductors

et al. 2007

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Using model calculations of a disordered d-wave superconductor with on-site Hubbard repulsion, we show how dopant disorder can stabilize novel states with antiferromagnetic order. We find that the critical strength of correlations or impurity potential necessary to create an ordered magnetic state in the presence of finite disorder is reduced compared to that required to create a single isolated magnetic droplet. This may explain why in cuprates like La2−xSrxCuO4(LSCO) low-energy probes have identified a static magnetic component which persists well into the superconducting state, whereas in cleaner systems like YBa2Cu3O 6+δ (YBCO) it is absent or minimal.PACS numbers: 74.25.Jb,74.25.Hc The occurrence of high-temperature superconductivity in cuprates near the antiferromagnetic (AF) phase of the parent compounds has prompted speculation since their discovery that superconductivity and magnetism were intimately related. For the most part, it has been assumed that the two forms of order compete and do not coexist, consistent with the vanishing of the Néel temperature T N before the onset of a superconducting critical temperature T c , and the suppression of T c near doping x = 1/8 where static stripe phases can be stable [1]. On the other hand, there have been persistent reports of static AF at low temperatures T in the superconducting phase at low doping, as measured by muon spin resonance (µSR) [2,3], nuclear magnetic resonance (NMR) [4,5], and elastic neutron scattering (NS) [6,7]. The NS experiments reveal an incommensurate (IC) ordering wavevector evident by a quartet of peaks surrounding (π, π). Since the neutron response is enhanced by an applied magnetic field [6,8,9] several authors have discussed it in terms of coexisting d-wave superconductivity (dSC) and field-induced spin density waves [10]. Recent magnetic Raman scattering data on LSCO has been discussed in terms of such effects as well [11]. However, static order also exists at zero field in the underdoped phase of LSCO [6,7], and has been attributed to disorder [6]. In optimally doped LSCO, Kimura et al. [12] did not detect ordered moments in pure and 1% Zn-substituted samples. An elastic peak similar to the pure underdoped material was observed when 1.7% Zn was added, however [12].Phenomena similar to those in LSCO have been observed in other materials, e.g. Y 1−x Ca x Ba 2 Cu 3 O 6 , and Bi 2 Sr 2 CaCu 2 O 8+x (BSCCO) where µSR directly reveals a slowing down and subsequent freezing of spin fluctuations as T is lowered [2,13]. On the other hand, experiments on optimally doped YBCO, even with significant percentages of Zn, have never detected static magnetic signals. While there have been reports of AF coexisting with dSC in underdoped YBCO, recent NS measurements on YBCO 6.5 found that AF order, while static from the point of view of NS timescales, 10 −10 s, was fluctuating faster than the timescale, 10 −6 s, for µSR. Thus, it appears that while in YBCO low-frequency AF fluctuations are present, they do not "freeze out". Recently, reports of st...

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Dilution-induced order in quasi-one-dimensional quantum antiferromagnets

Cited by 60 publications

References 11 publications

d-Wave superconductivity as a catalyst for antiferromagnetism in underdoped cuprates

d-Wave superconductivity as a catalyst for antiferromagnetism in underdoped cuprates

Disorder-Induced Revival of the Bose-Einstein Condensation inNi(Cl1−xBrx
Dupont
¹
,
Capponi
²
,
Laflorencie
³

2017
Phys. Rev. Lett.
14
5
28
0
View full text Add to dashboard Cite

Disorder-Induced Static Antiferromagnetism in Cuprate Superconductors

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Dilution-induced order in quasi-one-dimensional quantum antiferromagnets

Cited by 60 publications

References 11 publications

d-Wave superconductivity as a catalyst for antiferromagnetism in underdoped cuprates

d-Wave superconductivity as a catalyst for antiferromagnetism in underdoped cuprates

Disorder-Induced Revival of the Bose-Einstein Condensation inNi(Cl1−xBrxDupont1, Capponi2, Laflorencie3 2017Phys. Rev. Lett.145280View full textAdd to dashboardCite

Disorder-Induced Static Antiferromagnetism in Cuprate Superconductors

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Resources

About

Disorder-Induced Revival of the Bose-Einstein Condensation inNi(Cl1−xBrx
Dupont
¹
,
Capponi
²
,
Laflorencie
³

2017
Phys. Rev. Lett.
14
5
28
0
View full text Add to dashboard Cite