Unconventional Magnetic and Thermodynamic Properties ofS=1/2Spin Ladder with Ferromagnetic Legs

Abstract

We have succeeded in synthesizing single crystals of a new organic radical 3-Cl-4-F-V [3-(3-chloro-4-fluorophenyl)-1,5-diphenylverdazyl]. Through the ab initio molecular orbital calculation and the analysis of the magnetic properties, this compound was confirmed to be the first experimental realization of an S=1/2 spin-ladder system with ferromagnetic leg interactions. The field-temperature phase diagram indicated that the ground state is situated very close to the quantum critical point. Furthermore, we found an unexpected field-induced successive phase transition, which possibly originates from the interplay of low dimensionality and frustration.

Fine-Tuning of Magnetic Interactions in Organic Spin Ladders

“…(4) • . 23 These results indicate that the molecular arrangements of these materials are isomorphous to that of 3-Cl-4-F-V. 8 The verdazyl ring with four nitrogen atoms, the right side two phenyl rings, and the left side phenyl ring are labeled R 1 , R 2 , R 3 , and R 4 , respectively, for both molecules, as shown in Figs. 1(a) and 1(b).…”

“…[8][9][10] Figure 1(c) shows the remarkable uniform chain structure along the a-axis in 3-I-V, where the C-C and N-C short contacts less than 3.6 Å are labeled d 1 -d 3 and listed in Table I. The corresponding contacts for 3-Br-4-F-V and 3-I-LETTERS V are slightly longer and shorter than those in 3-Cl-4-F-V, respectively.…”

Field-induced incommensurate phase in the strong-rung spin ladder with ferromagnetic legs

“…We previously reported the first experimental realization of an S = 1/2 FM chain-based [16], where γ was evaluated as 0.55. However, in zero magnetic field the energy gap disappears and phase transitions to an ordered state are observed.…”

Three-dimensional Bose-Einstein condensation in the spin- 12 ferromagnetic-leg ladder 3-Br-4-F-V

“…Recently, spin-1/2 ferromagnetic-leg (FM-leg) ladders (J || < 0, J ⊥ > 0) have been synthesized for the first time, using verdazyl radical molecules [15][16][17][18]. Theoretically, FM-leg ladders with an isotropic leg interaction also have a spin gap, which stems from the rung-singlet state [19], and the ground state between H c1 and H c2 has also been predicted to be a TLL [20].…”