Chiral spin liquid in a two-dimensional two-component helical magnet

Димитрова, О. В.

doi:10.1103/physrevb.90.014409

Cited by 3 publications

(11 citation statements)

References 26 publications

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“…Our calculated critical exponents for the spiral ferromagnet to paramagnet quantum phase transition in the spin orbit coupled spin-1 Bose-Hubbard model (ν ≈ 2/3 and γ ≈ 1/2) point to the possible existence of a new universality class in this problem. Our results for the numerical value of the correlation length exponent are consistent with the universality class of classical uniaxial dipolar ferromangets [65][66][67] and the XY chiral spin liquid transition in two dimensions [68] but the current numerical accuracy of our calculations does not allow us to disentangle this from the possible three-dimensional Ising and XY universality classes. On physical grounds however, it is most natural to expect that our results are consistent with the chiral spin liquid class as this involves a helical magnetic transition.…”

Section: Phase Diagramsupporting

confidence: 51%

“…It is also possible that we need to compare different channels, as it is non-trivial to compare our estimate of γ to those of the RG since we are computing the order parameter susceptibility from S z (r)S z (r ) , whereas the RG in Ref. [68] computes a "twist" susceptibility, which corresponds to a correlation function quartic in spin operators. At this stage, we are inclined to believe that our system indeed belongs to a new universality class not studied before in the literature, but more work (and possibly more accurate numerical estimates of critical exponents) are necessary before any definitive conclusion can be reached.…”

Section: A Dmrgmentioning

confidence: 99%

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Strong-coupling phases of the spin-orbit-coupled spin-1 Bose-Hubbard chain: Odd-integer Mott lobes and helical magnetic phases

et al. 2017

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We study the odd integer filled Mott phases of a spin-1 Bose-Hubbard chain and determine their fate in the presence of a Raman induced spin-orbit coupling which has been achieved in ultracold atomic gases; this system is described by a quantum spin-1 chain with a spiral magnetic field. The spiral magnetic field initially induces helical order with either ferromagnetic or dimer order parameters, giving rise to a spiral paramagnet at large field. The spiral ferromagnet-to-paramagnet phase transition is in a novel universality class, with critical exponents associated with the divergence of the correlation length ν ≈ 2/3 and the order parameter susceptibility γ ≈ 1/2. We solve the effective spin model exactly using the density matrix renormalization group, and compare with both a large-S classical solution and a phenomenological Landau theory. We discuss how these exotic bosonic magnetic phases can be produced and probed in ultracold atomic experiments in optical lattices.Strongly-correlated quantum spin chains are an interacting many-body system that have been an instrumental platform to develop an understanding of topological properties [1], Berry phase effects [2], and quantum phase transitions [3]. One of the paradigmatic theoretical models in this context is the spin-1 bilinear-biquadratic Heisenberg chain [2-4](J is the unit of energy) which supports several conceptually important phases and phase transitions [5][6][7][8][9][10][11][12][13][14]. The physics associated with the Hamiltonian in Eq. (1) is not only theoretically tantalizing, but is also directly accessible to experiments. For example, the antiferromagnetic spin-1 chain (cos θ > 0) has been probed experimentally in insulating quantum magnets [15][16][17] that possess wellisolated, quasi-one-dimensional chains of S = 1 local moments. Interestingly, ultracold atomic gases are a natural platform for realizing the complementary ferromagnetic spin-1 chain (cos θ < 0), where the system is an effective description of the Mott insulating spin-1 Bose-Hubbard model [18][19][20][21][22][23]. Solid state experiments always contain at least some disorder that breaks the spin chain into segments [16], while the cold atomic gas setting is essentially pristine with no disorder in principle, so that the theoretical model defined by Eq. (1) (as well as its generalizations) can be studied directly. Until recently, it has been difficult to realize magnetic ordering in ultra-cold atomic gases [24,25], and a crucial element of physics is developing a theoretical understanding of the available strongly correlated phases. A virtue of the flexibility and the precise control in atomic and molecular experiments is that various physical effects can be engineered simulating desired features of solid-state systems despite the vastly different setting (i.e. atoms versus solids). Along these lines, recent experiments on cold atomic gases have demonstrated that, despite the atoms being electrically neutral, spin orbit coupling (SOC) can be engineered using two counter propagating...

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Section: Phase Diagramsupporting

confidence: 51%

Section: A Dmrgmentioning

confidence: 99%

Strong-coupling phases of the spin-orbit-coupled spin-1 Bose-Hubbard chain: Odd-integer Mott lobes and helical magnetic phases

et al. 2017

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“…In our previous study [9], we have not considered the vicinity of the Lifshitz point and have found the simplistic phase diagram ( fig.1d). In the current study, we extend the results and find the diagram (fig.2) consistent with [15,16]. We also investigate the critical properties of topological defects, namely domain walls and vortices.…”

Section: N = 2 K =supporting

confidence: 84%

“…In addition to the reentrant phase transition to the collinear quasi-longrange ordered phase, the authors have found that the anisotropy of the system leads to a non-Ising character of the chiral transition modified by a long-range interaction. In other words, the chiral transition falls to the universality class of the two-dimensional Ising model with strong long-range dipolar interactions [16]. But in our opinion, this conclusion is the consequence of the chosen approximation, when a domain wall along the helix direction is infinitely heavy.…”

Section: N = 2 K =mentioning

confidence: 75%

“…where k x,µ is defines similarly to (7) in the lattice direction e µ . Figure 1: Possible phase diagrams of the N = 2, K = 1 helimagnet discussed in the previous studies: a) [29,31]; b) [14]; c) [23]; d) [30,9]; e) [15,16]. Phases are denoted by the letters: F -ferromagnetic with quasi-long-range order, H -helicoidal, P -paramagnetic (disordered), L -chiral spin liquid, Qquasi-long-range planar order, S -smectic-like phase.…”

Section: Model and Methodsmentioning

confidence: 99%

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Topological defects and critical phenomena in two-dimensional frustrated helimagnets

Сорокин

2019

Journal of Magnetism and Magnetic Materials

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Using a simple model of a frustrated helimagnet, the critical behavior is numerically investigated for planar or isotropic spins, and for cases of one or two chiral order parameters. The helical structure in this model arises from the competition between exchange interactions of spins of the first two range orders in one direction (in both directions) of a square lattice. The main result is that the critical and temperature behavior is primarily determined by topological defects that are present in all cases. In the case of planar spins, vortices, fractional vortices and domain walls are present in the system. Their interaction leads to the appearance of the phase of a chiral spin liquid, or induces a single first-order transition, and in the vicinity of the Lifshitz point vortices lead to a reentrant phase transition to the phase with a collinear quasi-long-range order. When transitions in the chiral and continuous order parameters are separated in temperature, they are of the 2D Ising and Kosterlitz-Thouless types correspondingly. In the case of isotropic spins, so-called Z 2 vortices are present. They do not lead to the appearance of a phase with long-range or quasi-long-range order in the case of one chiral order parameter. However, their interaction leads to a sharp change in the temperature dependence of the correlation length (crossover). In the case of two chiral parameters, there are long-range chiral order of the Ising type (chiral spin liquid) and domain walls. However, as a result of the interaction of vortices and walls, the crossover and chiral transition occur at the same temperature as a first-order transition.

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Stiffness in vortex—like structures due to chirality-domains within a coupled helical rare-earth superlattice

Paul

2016

Sci Rep

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Vortex domain walls poses chirality or ‘handedness’ which can be exploited to act as memory units by changing their polarity with electric field or driving/manupulating the vortex itself by electric currents in multiferroics. Recently, domain walls formed by one dimensional array of vortex—like structures have been theoretically predicted to exist in disordered rare-earth helical magnets with topological defects. Here, in this report, we have used a combination of two rare-earth metals, e.g. superlattice that leads to long range magnetic order despite their competing anisotropies along the out-of-plane (Er) and in-plane (Tb) directions. Probing the vertically correlated magnetic structures by off-specular polarized neutron scattering we confirm the existence of such magnetic vortex—like domains associated with magnetic helical ordering within the Er layers. The vortex—like structures are predicted to have opposite chirality, side—by—side, and are fairly unaffected by the introduction of magnetic ordering between the interfacial Tb layers and also with the increase in magnetic field which is a direct consequence of screening of the vorticity in the system due to a helical background. Overall, the stability of these vortices over a wide range of temperatures, fields and interfacial coupling, opens up the opportunity for fundamental chiral spintronics in unconventional systems.

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Chiral spin liquid in a two-dimensional two-component helical magnet

Cited by 3 publications

References 26 publications

Strong-coupling phases of the spin-orbit-coupled spin-1 Bose-Hubbard chain: Odd-integer Mott lobes and helical magnetic phases

Strong-coupling phases of the spin-orbit-coupled spin-1 Bose-Hubbard chain: Odd-integer Mott lobes and helical magnetic phases

Topological defects and critical phenomena in two-dimensional frustrated helimagnets

Stiffness in vortex—like structures due to chirality-domains within a coupled helical rare-earth superlattice

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