Experimental phase diagram ofCu2(C5

Grégory Chaboussant

¹

,

P. A. Crowell

²

,

Laurent Lévy

³

et al.

Quantum phases and phase transitions of Mott insulators

“…It is clear that the effective potential of ϕ α has a minimum at a nonzero ϕ α , and that ϕ α ∝ N 0 , the Néel order parameter in (2). It is simple to carry out a small fluctuation analysis about this saddle point, and we obtain the doublet of gapless spin-wave modes advertised earlier.…”

“…In all phases the s boson is well condensed at zero momentum, and the important physics can be easily understood by examining the structure of the low energy action for the t α bosons. For the particular Hamiltonian (1), the spectrum of the t α bosons has a minimum at the momentum (0, π), and for large enough λ the t α condense at this wavevector: the representation (6) shows that this condensed state is the expected Néel state, with the magnetic moment oscillating as in (2). The condensation transition of the t α is therefore the quantum phase transition between the paramagnetic and Néel phases of the coupled dimer antiferromagnet.…”

“…While a quantitative synthesis of theory and experiment in the superconducting materials remains elusive, much progress has been made in describing a number of antiferromagnetic Mott insulators. A number of such insulators have been studied extensively in the past decade, with a few prominent examples being CaV 4 O 9 [1], (C 5 H 12 N 2 ) 2 Cu 2 Cl 4 [2,3,4], SrCu 2 (BO 3 ) 2 [5,6], TlCuCl 3 [7,8,9,10], and Cs 2 CuCl 4 [11,12]. In some cases, it has even been possible to tune these insulators across quantum phase transitions by applied pressure [8] or by an applied magnetic field [3,4,7,9].…”

Holographic antiferromagnetic quantum criticality andAdS2scaling limit

“…One of the most interesting and intensively discussed QPTs is the ordered-disordered QPT in antiferromagnetic materials induced by magnetic field, such as Cu 2 ðC 5 H 1 2N 2 Þ 2 Cl 4 [9], KCuCl 3 [10], TlCuCl 3 [11], BiCoPO 5 [12] and Er 2−2x Y 2x Ti 2 O 7 [13]. A schematic phase diagram in the vicinity of a QPT as a function of the magnetic field is shown in Fig.…”

Magnetization Process of the S = 1/2 Two-Leg Organic Spin-Ladder Compound BIP-BNO

“…[17][18][19][20][21] Cu2(C5H12N2)2Cl4, or CuHpCl, is one of the most studied compounds that were considered to be spin ladders. [22][23][24][25] Some recent experiments, however, have pointed out that CuHpCl should be described as a three dimensional spin system rather than a spin ladder. 26.27) In spite of many studies on S = 1/2 spin-ladder systems both theoretically and experimentally, there are few compounds with exchange constants (Jrung and Jleg) comparable to readily available magnetic field (B): B < 20 T. BPCB, (5IAP)2CuBr4・2H2O, and DMIPY are the materials that have such weak exchange constants and the ratios of the exchange constants Jrung/Jleg were estimated to be approximately 3.5, 13, and 0.52, respectively.…”