Spin-1/2 string correlations and singlet-triplet gaps of frustrated ladders with ferromagnetic legs and alternate ferromagnetic and antiferromagnetic rungs

被引:1
作者
Chatterjee, Monalisa [1 ]
Kumar, Manoranjan [1 ]
Soos, Zoltan G. [2 ]
机构
[1] SN Bose Natl Ctr Basic Sci, Block JD,Sect 3, Kolkata 700106, India
[2] Princeton Univ, Dept Chem, Princeton, NJ 08544 USA
关键词
QUANTUM SPIN; RENORMALIZATION-GROUP; PHASE; CHAIN; STATE; DIMERIZATION; TRANSITIONS; CONTINUUM; SYMMETRY; MODEL;
D O I
10.1103/PhysRevB.109.094439
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
The frustrated ladder with alternate ferromagnetic exchange -J(F) and antiferromagnetic exchange J(A) to first neighbors and ferromagnetic exchange -J(L) to second neighbors is studied by exact diagonalization and density matrix renormalization group calculations in systems of 2N spins-1/2 with periodic boundary conditions. The ground state is a singlet (S = 0) and the singlet-triplet gap epsilon(T) is finite for the exchanges considered. Spin-1/2 string correlation functions g(1)(N) and g(2)(N) are defined for an even number N of consecutive spins in systems with two spins per unit cell; the ladder has string order g(2)(infinity)>0 and g(1)(infinity)=0. The minimum N-& lowast; of g(2)(N) is related to the range of ground-state spin correlations. Convergence to g(2)(infinity) is from below, and g1(N) decreases exponentially for N >= N-& lowast;. Singlet valence bond (VB) diagrams account for the size dependencies. The frustrated ladder at special values of J(F), J(L), and J(A) reduces to well-known models such as the spin-1 Heisenberg antiferromagnet and the J(1)-J(2) model, among others. Numerical analysis of ladders matches previous results for spin-1 gaps or string correlation functions and extends them to spin-1/2 systems. The nondegenerate singlet ground state of the ladder is a bond-order wave, a Kekul & eacute; VB diagram at J(L)=J(F)/2 <= J(A), that is reversed on interchanging -J(F) and J(A). Inversion symmetry is spontaneously broken in the dimer phase of the J(1)-J(2) model where the Kekul & eacute; diagrams are the doubly degenerate ground states at J(2)/J(1 )= 1/2.
引用
收藏
页数:12
相关论文
共 51 条
[1]   CRITICAL-THEORY OF QUANTUM SPIN CHAINS [J].
AFFLECK, I ;
HALDANE, FDM .
PHYSICAL REVIEW B, 1987, 36 (10) :5291-5300
[2]   Metal theory [J].
Bethe, H. .
ZEITSCHRIFT FUR PHYSIK, 1931, 71 (3-4) :205-226
[3]   Crystal structure and magnetic properties of the spin-21 frustrated two-leg ladder compounds (C4H14N2)Cu2X6 (X= Cl and Br) [J].
Biswal, P. ;
Guchhait, S. ;
Ghosh, S. ;
Sarangi, S. N. ;
Samal, D. ;
Swain, Diptikanta ;
Kumar, Manoranjan ;
Nath, R. .
PHYSICAL REVIEW B, 2023, 108 (13)
[4]   A STUDY OF THE BILINEAR BIQUADRATIC SPIN-1 ANTIFERROMAGNETIC CHAIN USING THE VALENCE-BOND BASIS [J].
CHANG, K ;
AFFLECK, I ;
HAYDEN, GW ;
SOOS, ZG .
JOURNAL OF PHYSICS-CONDENSED MATTER, 1989, 1 (01) :153-167
[5]   Singlet quantum phases of the frustrated spin-1/2 ladder with ferromagnetic (F) exchange in legs and alternating F-AF exchange in rungs [J].
Chatterjee, Monalisa ;
Kumar, Manoranjan ;
Soos, Zoltan G. .
PHYSICA SCRIPTA, 2024, 99 (02)
[6]   DENSITY-MATRIX RENORMALIZATION-GROUP STUDIES OF THE SPIN-1/2 HEISENBERG SYSTEMS WITH DIMERIZATION AND FRUSTRATION [J].
CHITRA, R ;
PATI, S ;
KRISHNAMURTHY, HR ;
SEN, D ;
RAMASESHA, S .
PHYSICAL REVIEW B, 1995, 52 (09) :6581-6587
[7]   SUPERCONDUCTIVITY IN LADDERS AND COUPLED PLANES [J].
DAGOTTO, E ;
RIERA, J ;
SCALAPINO, D .
PHYSICAL REVIEW B, 1992, 45 (10) :5744-5745
[8]   EXPERIMENTS ON SIMPLE MAGNETIC MODEL SYSTEMS [J].
DEJONGH, LJ ;
MIEDEMA, AR .
ADVANCES IN PHYSICS, 1974, 23 (01) :1-260
[9]   PREROUGHENING TRANSITIONS IN CRYSTAL-SURFACES AND VALENCE-BOND PHASES IN QUANTUM SPIN CHAINS [J].
DENNIJS, M ;
ROMMELSE, K .
PHYSICAL REVIEW B, 1989, 40 (07) :4709-4734
[10]   Exactly solvable spin ladder model with degenerate ferromagnetic and singlet states [J].
Dmitriev, DV ;
Krivnov, VY ;
Ovchinnikov, AA .
EUROPEAN PHYSICAL JOURNAL B, 2000, 14 (01) :91-97