Abnormal magnetism and phase transformation of a Heisenberg-like model with internal spin fluctuation

Wang, Huaiyu; Chen, Ke‐Qiu; Wang, Enge

doi:10.1103/physrevb.66.092405

Cited by 14 publications

(3 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The method we use is the many-body Green's function theory, which has long been applied to treat the Heisenberg exchange model. [60][61][62][63][64] The retarded Green's functions or double-time Green's functions are, according to Bogolyubov and Tyablikov, 65,66 as follows:…”

Section: Model Hamiltonian and Computational Methodsmentioning

confidence: 99%

Magnetic properties of very-high-spin organic π-conjugated polymers based on Green’s function theory

Yao

Liu

2008

The Journal of Chemical Physics

View full text Add to dashboard Cite

Magnetic properties of two very-high-spin organic pi-conjugated polymers have been investigated theoretically by means of the many-body Green's function method with random phase approximation. The polymers are designed with a large density of cross-links and alternating connectivity of radical modules with unequal spin quantum numbers (S), macrocyclic S=2 or 3, and cross-linking S=1/2 modules, which permit large net S values for either antiferromagnetic or ferromagnetic exchange coupling between the modules. The numerical results reveal that, ascribing to the zero-temperature spin fluctuations, the sublattice magnetizations of the two polymers are both smaller than their classical spin values and the ground-state magnetizations of them are also smaller than their predicted values in the antiferromagnetic exchange coupling case. However, these magnetic behaviors do not occur in the ferromagnetic exchange coupling case. On the basis of our synthesis of the temperature dependence of the magnetic susceptibility multiplied by temperature, and through comparing the theoretical results with the experimental measurements, it is concluded that the magnetic exchange couplings between the modules within the two high-spin polymers should be ferromagnetic exchange couplings, which are consistent with other theoretical results drawn from the investigations into the ground-state properties of the two organic polymers.

show abstract

Section: Model Hamiltonian and Computational Methodsmentioning

confidence: 99%

Magnetic properties of very-high-spin organic π-conjugated polymers based on Green’s function theory

Yao

Liu

2008

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…[15][16][17] The retarded Green's functions or double-time Green's functions are, according to Bogolyubov and Tyablikov,18 as follows: [15][16][17] The retarded Green's functions or double-time Green's functions are, according to Bogolyubov and Tyablikov,18 as follows:…”

Section: Model and Theoretical Methodsmentioning

confidence: 99%

Magnetic properties and quantum phase transitions of purely organic molecule-based ferrimagnets based on Green’s function theory

Yao

Liu

2008

The Journal of Chemical Physics

View full text Add to dashboard Cite

Magnetic properties of a Heisenberg diamondlike spin chain model for purely organic molecule-based ferrimagnets are investigated by means of the many-body Green's function method within random phase approximation. The molecule-based ferrimagnet is composed of S=1 biradical and S=1/2 monoradical molecules alternating with intermolecular antiferromagnetic (AF) interactions, and the S=1 site is composed of two S=1/2 spins by a finite intramolecular ferromagnetic (F) interaction. The numerical results reveal that occurrence of ferrimagnetic spin alignments along the chain is determined by the intermolecular AF interactions. Owing to the very small intermolecular AF interactions, the curves of the product of magnetic susceptibility and temperature (chiT) against temperature display as a round peak at low temperatures, and the ferrimagnetic phase transition could only be detected at ultralow temperatures in practical organic compounds. Temperature- and magnetic-field-induced magnetic phase transitions are discussed, which are consistent with the experimental findings. The lower spatial symmetry of intermolecular interactions makes it easy to form spin pairs with a singlet (S=0) ground state along the chain and to reduce Curie temperature. The formations of molecular dimers and trimers along the chain have contributions to bring about F alignments with effective S=1/2 magnetic supramolecules and to enhance Curie temperature. In addition, the experimental data of the magnetic susceptibility measurements for a molecule-based ferrimagnet are also fairly compared with our theoretical results.

show abstract

“…[25][26][27][28] In this paper, we will apply TGFM to investigate the magnetic properties of La 1−x Sr x MnO 3 by means of the three-dimensional mixedspin Heisenberg model. Moreover, TGFM is valid over the whole temperature range and takes into account the spin fluctuation.…”

Section: Introductionmentioning

confidence: 99%

The three-dimensional mixed-spin Heisenberg model applied to the magnetic properties of La1−xSrxMnO3 in the random phase approximation

Chen

Wang

2010

Journal of Applied Physics

View full text Add to dashboard Cite

Articles you may be interested inThree-dimensional strain state and spacer thickness-dependent properties of epitaxial Pr0.7Sr0.3MnO3/La0.5Ca0.5MnO3/Pr0.7Sr0.3MnO3 trilayer structureThe magnetic properties of the manganese oxide compounds La 1−x Sr x MnO 3 are studied by means of the double-time Green's function. The phase diagram, magnetization, spin-wave dispersion, and spin-wave stiffness are obtained within the random phase approximation. Our results are in agreement with other theoretical and experimental results.

show abstract

Abnormal magnetism and phase transformation of a Heisenberg-like model with internal spin fluctuation

Cited by 14 publications

References 12 publications

Magnetic properties of very-high-spin organic π-conjugated polymers based on Green’s function theory

Magnetic properties of very-high-spin organic π-conjugated polymers based on Green’s function theory

Magnetic properties and quantum phase transitions of purely organic molecule-based ferrimagnets based on Green’s function theory

The three-dimensional mixed-spin Heisenberg model applied to the magnetic properties of La1−xSrxMnO3 in the random phase approximation

Contact Info

Product

Resources

About