Theory of inelastic light scattering in spin-1 systems: Resonant regimes and detection of quadrupolar order

Michaud, Frederic; Vernay, F.; Mila, Frédéric

doi:10.1103/physrevb.84.184424

Cited by 32 publications

(21 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…First, the similarity of the excitation energies close to 4600 cm −1 ∼ 4 J in both symmetries may be accidental but remains to be explained. Second, since intensity from chiral excitations according to the operatorĈ = S i · (S j × S k ) should not appear in first order 53,54 the cross section should be smaller than in all other symmetries.…”

Section: Discussionmentioning

confidence: 99%

Magnetic excitations and amplitude fluctuations in insulating cuprates

et al. 2018

View full text Add to dashboard Cite

We present results from light scattering experiments on three insulating antiferromagnetic cuprates, YBa$_2$Cu$_3$O$_{6.05}$, Bi$_2$Sr$_2$YCu$_2$O$_{8+\delta}$, and La$_2$CuO$_4$ as a function of polarization and excitation energy. The spectral shape in $B_{1g}$ symmetry is found to be nearly universal and independent of the excitation energy. The spectra agree quantitatively with predictions by field theory [\onlinecite{Weidinger:2015}] facilitating the precise extraction of the Heisenberg coupling $J$. The spectra in the other symmetries are not universal. The variations may be traced back to weak resonance effects and extrinsic contributions. For all three compounds we find support for the existence of chiral excitations appearing as a continuum in $A_{2g}$ symmetry having an onset slightly below $3J$. In La$_2$CuO$_4$ an additional isolated excitation appears on top of the $A_{2g}$ continuum.Comment: 8 pages, 7 figure

show abstract

Section: Discussionmentioning

confidence: 99%

Magnetic excitations and amplitude fluctuations in insulating cuprates

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Spin nematic phases have been identified in lattice spin 1 models (see, e.g, [3][4][5][6][7][8][9][10]) or in spin 1 Bose-Einstein condensates (BECs) [11] with antiferromagnetic spinexchange interactions [12][13][14][15][16][17][18][19][20][21]. In solid state systems, most magnetic probes couple only to the magnetization and are therefore unsuitable to reveal spin nematic order.…”

Section: Introductionmentioning

confidence: 99%

Spin-nematic order in antiferromagnetic spinor condensates

et al. 2016

View full text Add to dashboard Cite

Large spin systems can exhibit unconventional types of magnetic ordering different from the ferromagnetic or Néel-like antiferromagnetic order commonly found in spin 1/2 systems. Spin-nematic phases, for instance, do not break time-reversal invariance and their magnetic order parameter is characterized by a second rank tensor with the symmetry of an ellipsoid. Here we show direct experimental evidence for spin-nematic ordering in a spin-1 Bose-Einstein condensate of sodium atoms with antiferromagnetic interactions. In a mean field description this order is enforced by locking the relative phase between spin components. We reveal this mechanism by studying the spin noise after a spin rotation, which is shown to contain information hidden when looking only at averages. The method should be applicable to high spin systems in order to reveal complex magnetic phases.

show abstract

“…[41]. The quadrupolar orders can also be measured by Raman scattering, which is able to couple to spin and quadrupolar operators by tuning light polarization and incoming light frequency, thus showing qualitatively different features for magnetic and quadrupolar phases [55]. More direct evidence can be gained from the quadrupolar structure factor, which should exhibit Bragg peaks at the ordering wave vector [53], and, in principle, can be measured by resonant inelastic x-ray scattering experiments [56,57].…”

mentioning

confidence: 99%

Spin Ferroquadrupolar Order in the Nematic Phase of FeSe

Wang

Nevidomskyy

2016

Phys. Rev. Lett.

View full text Add to dashboard Cite

We provide evidence that spin ferroquadrupolar (FQ) order is the likely ground state in the nonmagnetic nematic phase of stoichiometric FeSe. By studying the variational mean-field phase diagram of a bilinearbiquadratic Heisenberg model up to the 2nd nearest neighbor, we find the FQ phase in close proximity to the columnar antiferromagnet commonly realized in iron-based superconductors; the stability of FQ phase is further verified by the density matrix renormalization group. The dynamical spin structure factor in the FQ state is calculated with flavor-wave theory, which yields a qualitatively consistent result with inelastic neutron scattering experiments on FeSe at both low and high energies. We verify that FQ can coexist with C 4 breaking environments in the mean-field calculation, and further discuss the possibility that quantum fluctuations in FQ act as a source of nematicity. Superconductivity in the iron-based superconductors [1,2] is widely recognized to have spin fluctuations at its origin [3,4], as it develops after the suppression of columnar antiferromagnetism (CAFM) by doping or applied pressure on the parent compounds [5][6][7][8]. The CAFM phase is characterized by the magnetic Bragg peaks at wave vectors Q 1,2 = (π, 0)/(0, π) in the one-iron Brillouin zone, seen ubiquitously in different families of the iron pnictides and chalcogenides [5,9,10]. The discovery of superconductivity in stoichiometric FeSe thus came as a surprise, because the long-range magnetic order is conspicuously absent in this material [11][12][13][14][15][16]. Another important feature, universally observed across different families of iron-based superconductors, is the appearance of an electronic nematic phase [17][18][19][20], which spontaneously breaks the lattice C 4 rotational symmetry. Usually, nematicity appears in close proximity to magnetism above the Néel temperature; however, in FeSe, the nematic phase appears without any accompanying magnetism and coexists with superconductivity [12][13][14][15]. It is thus important to understand the origin of this nonmagnetic nematic phase, in particular, to gain insight into its effect on superconductivity.It turns out that magnetic order can be induced by applying hydrostatic pressure to FeSe [12][13][14]. It has also been suggested based on ab initio calculations that the nonmagnetic phase in FeSe lies in close proximity to the CAFM phase [21][22][23]. Further evidence of proximity to long-range magnetic order comes from inelastic neutron scattering (INS) experiments, which found large spectral weight at wave vectors Q 1,2 [24][25][26][27]. Two natural questions arise: In the theoretical phase diagram, is there a nonmagnetic phase that neighbors on the CAFM? And, furthermore, how does such a nonmagnetic phase give rise to nematicity?In an attempt to answer these questions, several theoretical scenarios have been proposed for nonmagnetic ground states that may appear as a result of frustration: a nematic quantum paramagnet [28], a spin quadrupolar state with wave vectors Q 1,2...

show abstract

Theory of inelastic light scattering in spin-1 systems: Resonant regimes and detection of quadrupolar order

Cited by 32 publications

References 37 publications

Magnetic excitations and amplitude fluctuations in insulating cuprates

Magnetic excitations and amplitude fluctuations in insulating cuprates

Spin-nematic order in antiferromagnetic spinor condensates

Spin Ferroquadrupolar Order in the Nematic Phase of FeSe

Contact Info

Product

Resources

About