DISORDERED FLAT PHASE IN A SOLID-ON-SOLID MODEL OF FCC(110) SURFACES AND DIMER STATES IN QUANTUM SPIN-1/2 CHAINS

Article

关键词: 110 SURFACES;    RECONSTRUCTED SURFACES;    ROUGHENING TRANSITION;    CRYSTAL-SURFACES;    FERMI GAS;    AU(110);    DECONSTRUCTION;    BEHAVIOR;    DIAGRAM;   

DOI  :  10.1103/PhysRevB.49.13886

来源: SCIE

【 摘 要 】

We present a restricted solid-on-solid Hamiltonian for fcc(110) surfaces. It is the simplest generalization of the exactly solvable body-centered solid-on-solid model which is able to describe a (2 X 1) missing-row reconstructed surface. We study this model by mapping it onto a quantum spin-1/2 chain of the Heisenberg type, with second and third neighbor S(i)(z)S(j)z couplings. The ground-state phase diagram of the spin-chain model is studied by exact diagonalization of finite chains up to N = 28 sites, as well as through analytical techniques. We find four phases in the phase diagram: two ordered phases in which the spins have a Neel type of long-range order (an unreconstructed and a missing-row reconstructed phase, in the surface language), a spin-liquid phase (representing a rough surface), and an intermediate dimer phase which breaks translational invariance and has a doubly degenerate ground state, corresponding to a disordered flat surface. The transition from the (2 x 1) reconstructed phase to the disordered flat phase belongs to the two-dimensional Ising universality class. A critical (preroughening) line with varying exponents separates the unreconstructed phase from the disordered flat phase. The possible experimental signatures of the disordered flat phase are discussed.

【 授权许可】

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