Quantum critical phenomena in a spin-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mfrac><mml:mn>1</mml:mn><mml:mn>2</mml:mn></mml:mfrac></mml:math> frustrated square lattice with spatial anisotropy
Hironori Yamaguchi, Yasuhiko Iwasaki, Yohei Kono, Tsuyoshi Okubo, S. Miyamoto, Yuko Hosokoshi, Akira Matsuo, T. Sakakibara, Takanori Kida, Masayuki Hagiwara
Abstract
We present a model compound with a spin-$\frac{1}{2}$ spatially anisotropic frustrated square lattice, in which three antiferromagnetic interactions and one ferromagnetic interaction are competing. We observe an unconventional gradual increase in the low-temperature magnetization curve reminiscent of the quantum critical behavior between gapped and gapless phases. In addition, the specific heat and electron spin resonance signals indicate one-dimensional characteristics. These results demonstrate quantum critical behavior associated with one dimensionalization caused by frustrated interactions in the spin-$\frac{1}{2}$ spatially anisotropic square lattice.