Magnetism and thermodynamics of spin-(12,1)decorated Heisenberg chain with spin-1 pendants

Abstract

The magnetic and thermodynamic properties of a ferrimagnetic decorated spin-͑ 1 2 ,1͒ Heisenberg chain with spin-1 pendant spins are investigated for three cases: ͑A͒ J 1 , J 2 Ͼ 0; ͑B͒ J 1 Ͼ 0 and J 2 Ͻ 0; and ͑C͒ J 1 Ͻ 0 and J 2 Ͼ 0, where J 1 and J 2 are the exchange couplings between spins in the chain and along the rung, respectively. The low-lying and magnetic properties are explored jointly by the real-space renormalization group, spin wave, and density-matrix renormalization-group methods, while the transfer-matrix renormalization-group method is invoked to study the thermodynamics. It is found that the magnon spectra consist of a gapless and two gapped branches. Two branches in case ͑C͒ have intersections. The coupling dependence of low-energy gaps are analyzed. In a magnetic field, a m = 3 2 ͑m is the magnetization per unit cell͒ plateau is observed for case ͑A͒, while two plateaux at m = 1 2 and 3 2 are observed for cases ͑B͒ and ͑C͒. Between the two plateaux in cases ͑B͒ and ͑C͒, the sublattice magnetizations for the spins coupled by ferromagnetic interactions have decreasing regions with increasing the magnetic field. At finite temperature, the zero-field susceptibility temperature product T and specific heat exhibit distinct exotic features with varying the couplings and temperature for different cases. T is found to converge as T → 0, which is different from the divergent behavior in the spin-͑ 1 2 ,1͒ mixed-spin chain without pendants. The observed thermodynamic behaviors are also discussed with the help of their low-lying excitations.

Combined study of Schwinger-boson mean-field theory and linearized tensor renormalization group on Heisenberg ferromagnetic mixed spin (S, σ) chains

“…1 To gain insight into the interplay of the two kinds of quantum chains with spin integer and half-integer, people turn to inspect the antiferromagnetic quantum mixed-spin chains. [2][3][4][5][6][7][8][9] Such systems usually have ferrimagnetic ground states due to uncompensated spins. The spin wave theory exposes the existence of two kinds of excitations, say, the ferromagnetic gapless excitations and antiferromagnetic gapped excitations.…”

Ferro- and Antiferromagnetic Aspects of Alternating Spin Systems

“…Susceptibility was shown to has a minimum at intermediate temperature [3][4][5]7]. Specific heat was having a maximum [3,4,7,[9][10][11][12][13] at mid temperature showing a Schottky-like peak. The spin correlation length behaves as 1 T  at low temperature [6,8].…”

“…Ferrimagnets are believed to have a combined effect of both behaviors [4,8,9,17,21,18], ferromagnetic and antiferromagnetic. Susceptibility times temperature decreases at low temperature showing a minimum and them starts to increase showing that the antiferromagnetic behavior is not smeared out after the minimum.…”

“…The thermal behavior was also investigated for ferrimagnetic chains [3][4][5][6][7][8][9][10][11][12][13]. Besides verifying the existence of two (gapped and gapless) excitation modes, the specific heat and magnetic susceptibility of ferrimagnetic chains were shown to depend upon temperature as 1 2 T and respectively at low temperatures using modified spinwave theory (MSWT) [6,7], density matrix renormalize-2 T  tion group (DMRG) [7], quantum Monte Carlo method (QMC) [6,7,11], and Schwinger boson mead field theory (SB) [5].…”

Thermal Properties of Ferrimagnetic Systems

“…Thermal properties of ferrimagnetic chains were theoretically investigated recently employing various methods like the modified spin-wave theory (MSWT) [1][2][3][4], density matrix renormalization group (DMRG) [2,3], quantum Monte Carlo method (QMC) [1,2,5], and Schwinger boson mead field theory (SB) [6]. The specific heat v and magnetic susceptibility C  were shown to depend upon temperature as 1 2 T and respectively at low temperatures, and 2 T  T  and v were shown to have, respectively, a rounded minimum [2,[6][7][8] and a Schottkylike peak [2][3][4][5]7,8] at intermediate temperatures.…”