Extreme Ultraviolet Absorption Spectra of K–Rb and K–Cs alloys

Electronic structure and exchange interactions of the ladder vanadates CaV2O5and MgV2O5

“…Our results suggests CaV 2 O 5 is a system of weakly coupled dimers along the rung of the ladder with a very strong interaction inside the dimer. The analysis [16] based on fitting the results of model calculations to the experimental susceptibility measurements for CaV 2 O 5 confirms the coupled dimer picture and one of the obtained set of parameters (J2=665 K, J3=135 K, J1=-25 K) is very close to our ab-initio calculated parameters values. However for MgV 2 O 5 our calculations suggest J2 J1 =1.53 and J3 J1 =2.40 which puts MgV 2 O 5 outside the scope of the ladder limit, consistent with the helical ordered gapless phase according to the phase diagram obtained by the Schwinger-boson mean field theory [17].…”

Direct Observation of the Quantum Phase Transition of SrCu2(BO3)2 by High-Pressure and Terahertz Electron Spin Resonance

“…14) The slight differences stem from the DM interaction that was taken into account in our calculation. Although our estimation gives the smallest values among the estimations of J and α for this compound, [14][15][16][17] they are the unique values that reproduced completely both energy gaps to the one-triplet excited states and the two-triplet bound state. Moreover, our estimation explains the fine splitting of the one-triplet excitation at zero field.…”

“…There has been a long debate on an intermediate phase between these states because strong frustration within this system prevents theoretical analyses that approach the quantum critical point (QCP) precisely. 8,[10][11][12][13] J and the ratio α = J ′ /J are estimated to be J = 71 − 85 K and α = 0.60 − 0.64 [14][15][16][17] for SrCu 2 (BO 3 ) 2 . Through intensive studies on the intermediate phase, there is a consensus that a QCP of an intermediate phase exists around α c (theory) ∼ 0.68 just above the ratio of this compound and it is the plaquette singlet phase.…”

“…One is that the model Hamiltonian H requires additional terms to describe the real material. To improve the discrepancy quantitatively, the intradimer DM interaction, the in-plane component of the interdimer DM interaction 31) or the interplane exchange interaction 14,15) might be required. The other is the possibility that the intradimer in-teraction J of the two orthogonal dimers become inequivalent by applying the pressure.…”

Multi-triplet bound states and finite-temperature dynamics in highly frustrated quantum spin ladders

“…This material is known to be located close to a first-order quantum phase transition out of its rungsinglet phase (to a plaquette valence-bond state), and to have an anomalously low value, T 1/2 /∆ 0 = 7 K/35 K = 0.2 [25], of the ratio between the half-height temperature of the one-triplon intensity and the size of the onetriplon gap. The conventional discussion of this material is phrased using 1/j , with the phase transition occurring at 1/j c = 0.675 [96] and the best estimates of 1/j (= 0.635 [22,97]) falling within 5% of this value. While it is tempting to place SrCu 2 (BO 3 ) 2 directly on Fig.…”