Magnetic entropy landscape and Grüneisen parameter of a quantum spin ladder

Ryll, H.; Kiefer, K.; Rüegg, Christian; Ward, Simon; Krämer, Karl; Biner, Daniel; Bouillot, Pierre; Coira, Emanuele; Giamarchi, Thierry; Kollath, Corinna

doi:10.1103/physrevb.89.144416

Cited by 29 publications

(28 citation statements)

References 31 publications

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“…In addition to this, it is also possible to change the interaction directly by using Feshbach resonance [23,24]. This possibility suggests a new avenue for studying a novel interacting GP in addition to those defined by changes in volume or magnetic field [8,[11][12][13][14][15][16]18,[25][26][27][28][29][30]. Furthermore, we establish an exact identity between these various GPs, making use of the scaling properties of the quantum gas system.…”

Section: Introductionmentioning

confidence: 90%

“…There are other parameters, in addition to volume, that can be used to change the state of the system. As an example, the well-known magnetic GP discussed in experiments [14][15][16]18] can be introduced analogously by replacing the volume V by the magnetic field H in the definition (6),…”

Section: A Grüneisen Parameters In the Grand-canonical Ensemblementioning

confidence: 99%

“…Heavy-fermion metals are extremely sensitive to a small change in pressure, and this pressure sensitivity is reflected in highly enhanced values of the GP [14]. At low temperatures, divergence of the GP stronger than logarithmic upon cooling in the quantum regime is used for experimental identification of quantum critical points [10,[15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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Grüneisen parameters: Origin, identity, and quantum refrigeration

Zhang²,

Guan

2020

Phys. Rev. Research

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In solid-state physics, the Grüneisen parameter (GP) was first introduced to study the effect of volume change of a crystal lattice on its vibrational frequencies and has since been widely used to investigate the characteristic energy scales of systems associated with the changes of external potentials. However, the GP is less investigated in gas systems and especially strongly interacting quantum gases. Here we report on some general results on the origin of the GP, an identity, and caloric effects in ultracold quantum gases. We prove that there exists a simple identity among three different types of GPs, quantifying the caloric effect induced by variations of volume, magnetic field, and interaction, respectively. Using exact Bethe ansatz solutions, we present a rigorous study of these different GPs and the quantum refrigeration in one-dimensional Bose and Fermi gases. Based on the exact equations of states of these systems, we further obtain analytic results for singular behavior of the GPs and the caloric effects at quantum criticality. We also predict the existence of the lowest temperature for cooling near a quantum phase transition. It turns out that the interaction ramp up and down in quantum gases provide a promising protocol of quantum refrigeration in addition to the usual adiabatic demagnetization cooling in solid-state materials.

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Section: Introductionmentioning

confidence: 90%

Section: A Grüneisen Parameters In the Grand-canonical Ensemblementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Grüneisen parameters: Origin, identity, and quantum refrigeration

Zhang²,

Guan

2020

Phys. Rev. Research

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“…Above a saturation field B c2 the system becomes gapped, once again. The X=Cl compound is characterized [6,7] by J leg /J rung ≈0.39 and a critical field of B c =1.73 T. Taking these two compounds as end points in a series (Hpip) 2 CuBr 4(1−x) Cl 4x , the controlled introduction of disorder via halide substitution x, offers opportunities for studying the effects of disorder in LL physics [6]. The substitution of the Br and Cl halide ions, which mediate the superexchange interactions between the Cu 2+ spin sites, facilitates disorder via randomized interaction strengths whilst leaving the spin ladder structure qualitatively unchanged.…”

Section: Introductionmentioning

confidence: 99%

Quantum magnetism in molecular spin ladders probed with muon-spin spectroscopy

et al. 2018

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We present the results of muon-spin spectroscopy (μ + SR) measurements on the molecular spin ladder system (Hpip) 2 CuBr 4(1−x) Cl 4x , [Hpip=(C 5 H 12 N)]. Using transverse field μ + SR we are able to identify characteristic behaviour in each of the regions of the phase diagram of the x=0 strong-rung spin ladder system (Hpip) 2 CuBr 4 . Comparison of our results to those of the dimer-based molecular magnet Cu(pyz)(gly)(ClO 4 ) shows several common features. We locate the crossovers in partially disordered (Hpip) 2 CuBr 4(1−x) Cl 4x (x=0.05), where a region of behaviour intermediate between quantum disordered and Luttinger liquid-like is identified. Our interpretation of the results incorporates an analysis of the probable muon stopping states in (Hpip) 2 CuBr 4 based on density functional calculations and suggests how the muon plus its local distortion can lead to a local probe unit with good sensitivity to the magnetic state. Using longitudinal field μ + SR we compare the dynamic response of the x=1 strong-rung material (Hpip) 2 CuCl 4 to that of the strong-leg material (C 7 H 10 N) 2 CuBr 4 (known as DIMPY) and demonstrate that our results are in agreement with predictions based on interacting fermionic quasiparticle excitations in these materials.

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“…Second, the ratio γ ≃ 0.4 [41] is perfectly suited for observing bound states in the two-magnon sector (whose weight scales with γ 2 ), without strong interference from scattering states. Third, the low energy scales in BPCC [41,42] allow one to work well within the FP phase at laboratory magnetic fields.…”

mentioning

confidence: 99%

Bound States and Field-Polarized Haldane Modes in a Quantum Spin Ladder

Ward¹,

Mena²,

Bouillot³

et al. 2017

Phys. Rev. Lett.

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The challenge of one-dimensional systems is to understand their physics beyond the level of known elementary excitations. By high-resolution neutron spectroscopy in a quantum spin-ladder material, we probe the leading multiparticle excitation by characterizing the two-magnon bound state at zero field. By applying high magnetic fields, we create and select the singlet (longitudinal) and triplet (transverse) excitations of the fully spin-polarized ladder, which have not been observed previously and are close analogs of the modes anticipated in a polarized Haldane chain. Theoretical modeling of the dynamical response demonstrates our complete quantitative understanding of these states. , and ultracold atoms [5]. Looking forward, the next frontier is to understand and control the physics of these systems on all energy scales, including their multiparticle excitations and topological states.Quantum magnets provide an excellent arena not only for quantitative measurements of the strongly correlated quantum wave function but also for its systematic control by applied external parameters [6][7][8]. Among the systems whose elementary magnetic excitations are already well characterized, one key model is the S ¼ 1=2 "ladder," consisting of two coupled spin chains [9], with detailed experimental studies performed on genuine ladder materials including La 4 Sr 10 Cu 24 O 41 [10], ðC 5 H 12 NÞ 2 CuBr 4 (BPCB) [11][12][13][14][15][16][17], and ðC 7 H 10 NÞ 2 CuBr 4 (DIMPY) [18][19][20][21]. The ladder has many parallels to another cornerstone model, the Haldane (S ¼ 1) chain [22,23], and significant progress has been made in calculating the dynamical response of both systems [24]. However, genuine Haldane materials with accessible energy scales have proven difficult to find [25][26][27], and thus the response in strong magnetic fields remains an open problem [28,29].In this Letter, we report on measurements of single-and multimagnon excitations in the spin ladder bis-piperidinium copper tetrachloride (BPCC). By exploiting the elegant parity selectivity of the ladder geometry, at zero field we demonstrate the presence of a strong two-magnon boundstate triplet over half of the Brillouin zone and quantify its spectral weight. At high fields, we demonstrate the selection criteria for the singlet excitation, or amplitude mode, of the fully field-polarized (FP) phase, as well as for its triplet (transverse) mode. Both are unknown in a conventional ferromagnet and have direct analogs in the FP Haldane chain. By detailed analytical and numerical modeling, we describe our intensity measurements with quantitative accuracy.The spin ladder has two basic magnetic interactions, the rung (J r ) and leg (J l ) couplings, and one ratio, γ ¼ J l =J r . BPCB (γ ≃ 0.26) and DIMPY (γ ≃ 1.7) exemplify contrasting regimes of ladder behavior. The deuterated chloride analog of BPCB, ðC 5 D 12 NÞ 2 CuCl 4 (BPCC) crystallizes in the same monoclinic space group, P2 1 =c, shown in Fig. S1 of the Supplemental Material (SM) [30]. Two halide bridges between p...

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Magnetic entropy landscape and Grüneisen parameter of a quantum spin ladder

Cited by 29 publications

References 31 publications

Grüneisen parameters: Origin, identity, and quantum refrigeration

Grüneisen parameters: Origin, identity, and quantum refrigeration

Quantum magnetism in molecular spin ladders probed with muon-spin spectroscopy

Bound States and Field-Polarized Haldane Modes in a Quantum Spin Ladder

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