Toshiya Hikihara

Vector chiral and multipolar orders in the spin-1 2 frustrated ferromagnetic chain in magnetic field

We study the one-dimensional spin-1/2 Heisenberg chain with competing ferromagnetic nearest-neighbor

Ground-state properties of nanographite systems with zigzag edges

{J}_{1}

Ground-state phase diagrams of frustrated spin- S XXZ chains: Chiral ordered phases

and antiferromagnetic next-nearest-neighbor

Ferromagnetism in armchair graphene nanoribbons

{J}_{2}

Ground State Phase Diagram of Frustrated S = 1 XXZ chains: Chiral Ordered Phases

exchange couplings in the presence of magnetic field. We use both numerical approaches (the density-matrix renormalization-group method and exact diagonalization) and effective-field-theory approach and obtain the ground-state phase diagram for wide parameter range of the coupling ratio

Fixed Point of the Finite System DMRG

{J}_{1}/{J}_{2}

Spin correlations in the two-leg antiferromagnetic ladder in a magnetic field

. The phase diagram is rich and has a variety of phases, including the vector chiral phase, the nematic phase, and other multipolar phases. In the vector chiral phase, which appears in relatively weak magnetic field, the ground state exhibits long-range order (LRO) of vector chirality which spontaneously breaks a parity symmetry. The nematic phase shows a quasi-LRO of antiferronematic spin correlation and arises as a result of formation of two-magnon bound states in high magnetic fields. Similarly, the higher multipolar phases, such as triatic

Ground-State and Thermodynamic Properties of the Quantum Mixed Spin-1/2-1/2-1-1 Chain.

(p=3)

Correlation amplitudes for the spin- 1 2 XXZ chain in a magnetic field

and quartic

Ground state of an S=1/2 distorted diamond chain in a finite magnetic field

(p=4)