Magnetic Properties of Hematite Single Crystals. I. Magnetization Isotherms, Antiferromagnetic Susceptibility, and Weak Ferromagnetism of a Natural Crystal

Lin, S. T.

doi:10.1103/physrev.116.1447

Cited by 50 publications

(19 citation statements)

References 17 publications

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“…The magnetization in hematite crystals at room temperature is expressed as the sum of two terms [ Lin , ; Tasaki and Iida , ; Townsend , ]:

m = m_{o} + χ H

where χ is the magnetic susceptibility and H is the applied field. The first term m o is the weak ferromagnetic moment constrained within the basal plane that arises from a canting effect ( m o ), and the second term is the induced magnetization due to the applied field.…”

Section: Samples and Methodsmentioning

confidence: 99%

Evidence for weak ferromagnetic moment within the basal plane of hematite natural crystals at low temperature

Martín-Hernández

Hirt

2013

Geochem Geophys Geosyst

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[1] Low-temperature magnetization of hematite within the basal plane has been studied in a collection of natural crystals by means of torque magnetometry. Comparison between the torque curves at room temperature and at 77 K allows identification of a weak ferromagnetic moment constrained within the basal plane at temperatures well below the Morin transition. Annealing the samples produces the expected reduction of the weak ferromagnetic moment, but there is also a relationship between the ferromagnetic moment before and after annealing. Low-temperature measurements after the annealing experiment reveal the presence of a weak ferromagnetic moment that survives the annealing. This observation suggests the magnetic structure of natural hematite crystals below the Morin transition can still be a carrier of magnetization. Martin-Hernandez, F., and A. M. Hirt (2013), Evidence for weak ferromagnetic moment within the basal plane of hematite natural crystals at low temperature,

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“…The magnetization in hematite crystals at room temperature is expressed as the sum of two terms [ Lin , ; Tasaki and Iida , ; Townsend , ]:

m = m_{o} + χ H

Section: Samples and Methodsmentioning

confidence: 99%

Evidence for weak ferromagnetic moment within the basal plane of hematite natural crystals at low temperature

Martín-Hernández

Hirt

2013

Geochem Geophys Geosyst

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“…The above characteristics resemble that of a material with weak ferromagnetism superimposed on a n anti-ferromagnetism observed in the region of small anisotropy energy [9].…”

Section: Magnetic Susceptibilitymentioning

confidence: 75%

Specific Heat and Magnetic Susceptibility Studies on Bromobis (1,4‐Diazacycloheptane) Copper(II) Perchlorate, [Cu(dach)₂Br](C10₄), at Low Temperatures

Khattak

Hussain

Hunter

et al. 1985

Physica Status Solidi (b)

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Specific heat and magnetization investigations are made on polycrystalline [Cu(dach),Br](ClO,) a t low temperatures. For temperatures above 25 K, the dc magnetization shows a Curie-Weiss behaviour with a Curie constant of 7.92 x lo3 e.m.u. K/g and a paramagnetic Curie temperature of -60.8 K. The downturn of 1/x vs. T below 25 K is indicative of ferrimagnetic system. The specific heat between 4 and 8 K can be described by the relation: C = 11.9T3 mJ/mol K with the cubic term leading to a Debye temperature of OD = 194 K. Below 4 K the specific heat rises very rapidly suggesting magnetic ordering. This is substantiated by the presence of a sharp peak a t 0.95 K in the ac susceptibility results which can be interpreted as being due to a ferrimagnetic phase transition. Both the magnetization and specific heat investigations indicate the behavior of the system to be ferromagnetic a t low temperatures which is interpreted as the result of the canted antiferromagnetism of sublattice moments. 1/x en fonction de T en dessous de 25 K indique une nature ferrimagnetique du systkme B ces temperatures. La variation de la chaleur specifique entre 4 et 8 K peut &re decrite par la relation: C = 11,9 T 3 mJ/mole K, la temperature de Debye &ant alors de 194 K. La chaleur specifique augmente trhs rapidement en dessous de 4 K, ce qui suggkre un re-arrangement magnetique. Cela est aussi suggCr6 par la presence d'un intense pic, B 0,95 K , dans la variation de la susceptibilite dc, ce qui pourrait &re interpret6 comme 6tant dQ A une transition de phase ferrimagnbtique. Cette double etude de la chaleur sp6cifique et de la magn6tisation indique que le systhme se comporte comme un ferromagnktique B basses temperatures. Ce comportement resulterait d u non-alignement des spins dans le sous-rbseau crystallin.

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“…The interaction (4.6) is called the Dzyaloshinsky-Moriya interaction [127,128]. Hematite is one of the most well known minerals, 124,126,[129][130][131] which is still being intensively studied 132 even at the present time. [133][134][135][136] Thus, there exist a large number of substances and materials that possess different types of magnetic behavior: diamagnetism, paramagnetism, ferromagnetism, antiferromagnetism, ferrimagnetism, and weak ferromagnetism.…”

Section: The Methods Of Model Hamiltoniansmentioning

confidence: 99%

Statistical mechanics and the physics of many-particle model systems

Kuzemsky

2009

Phys. Part. Nuclei

155

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The development of methods of quantum statistical mechanics is considered in light of their applications to quantum solid-state theory. We discuss fundamental problems of the physics of magnetic materials and the methods of the quantum theory of magnetism, including the method of two-time temperature Green's functions, which is widely used in various physical problems of many-particle systems with interaction. Quantum cooperative effects and quasiparticle dynamics in the basic microscopic models of quantum theory of magnetism: the Heisenberg model, the Hubbard model, the Anderson Model, and the spin-fermion model are considered in the framework of novel self-consistent-field approximation. We present a comparative analysis of these models; in particular, we compare their applicability for description of complex magnetic materials. The concepts of broken symmetry, quantum protectorate, and quasiaverages are analyzed in the context of quantum theory of magnetism and theory of superconductivity. The notion of broken symmetry is presented within the nonequilibrium statistical operator approach developed by D.N. Zubarev. In the framework of the latter approach we discuss the derivation of kinetic equations for a system in a thermal bath. Finally, the results of investigation of the dynamic behavior of a particle in an environment, taking into account dissipative effects, are presented.Keywords: Quantum statistical physics; quantum theory of magnetism; theory of superconductivity; Green's function method; Hubbard model and other many-particle models on a lattice; symmetry principles; breaking of symmetries; Bogoliubov's quasiaverages; quasiparticle many-body dynamics; magnetic polaron; microscopic theory of the antiferromagnetism.

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Magnetic Properties of Hematite Single Crystals. I. Magnetization Isotherms, Antiferromagnetic Susceptibility, and Weak Ferromagnetism of a Natural Crystal

Cited by 50 publications

References 17 publications

Evidence for weak ferromagnetic moment within the basal plane of hematite natural crystals at low temperature

Evidence for weak ferromagnetic moment within the basal plane of hematite natural crystals at low temperature

Specific Heat and Magnetic Susceptibility Studies on Bromobis (1,4‐Diazacycloheptane) Copper(II) Perchlorate, [Cu(dach)₂Br](C10₄), at Low Temperatures

Statistical mechanics and the physics of many-particle model systems

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Magnetic Properties of Hematite Single Crystals. I. Magnetization Isotherms, Antiferromagnetic Susceptibility, and Weak Ferromagnetism of a Natural Crystal

Cited by 50 publications

References 17 publications

Evidence for weak ferromagnetic moment within the basal plane of hematite natural crystals at low temperature

Evidence for weak ferromagnetic moment within the basal plane of hematite natural crystals at low temperature

Specific Heat and Magnetic Susceptibility Studies on Bromobis (1,4‐Diazacycloheptane) Copper(II) Perchlorate, [Cu(dach)2Br](C104), at Low Temperatures

Statistical mechanics and the physics of many-particle model systems

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Specific Heat and Magnetic Susceptibility Studies on Bromobis (1,4‐Diazacycloheptane) Copper(II) Perchlorate, [Cu(dach)₂Br](C10₄), at Low Temperatures