One‐Dimensional Mechanism of Antiferroelectric Ordering in a Non‐Polar Crystal

Kholopov, E. V.; Panich, A. M.; Мороз, Н. К.; Kriger, Yu. G.

doi:10.1002/pssb.2221370238

Cited by 4 publications

(5 citation statements)

References 4 publications

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“…The two thallium isotopes are unlike since they have different gyromagnetic ratios. Their natural abundances are f = 29.5% for 203 Tl and (1 − f ) = 70.5% for 205 Tl, that should yield [10,11,17,[19][20][21][22]. However, the experiments show that the line widths of 203 Tl and 205 Tl isotopes are close to each other.…”

Section: Results Of the Experimentsmentioning

confidence: 93%

“…This means that another mechanism determines the line shape. As known, the NMR spectra in most Tl-containing compounds are strongly caused by significant indirect exchange interactions among Tl isotopes [10,11,17,[19][20][21][22]. Van Vleck has shown [23] that exchange interaction J jk between like and unlike spins yields different contributions to the width and second moment of the NMR line.…”

Section: Results Of the Experimentsmentioning

confidence: 99%

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Indirect nuclear exchange coupling and electronic structure of the layered semiconductor TlS: NMR study and band structure calculation

Panich

Kashida

2004

J. Phys.: Condens. Matter

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We have studied the electronic structure of the layered semiconductor TlS by means of 203 Tl and 205 Tl NMR and band structure calculation. The crystal structure of this compound is built from the metal-chalcogen layers formed of linked Tl 3+ S 2− 4 tetrahedra and Tl + ions located between the layers. Our experiments show significant interlayer indirect exchange coupling of thallium nuclei. Since the distances between thallium ions essentially exceed the sum of their ionic radii, it is concluded that such coupling is realized due to the overlap of the Tl electron wavefunctions across the intervening S atom. The exchange interaction has been evaluated by means of the quantitative spectral analysis. The band structure calculation shows that the top of the valence band is composed of mixed Tl + 6s6p z -S 3s3p z -Tl 3+ 6s6p z states, yielding overlap of the Tl + -S-Tl 3+ type. Such electronic structure gives rise to the effective interlayer coupling of Tl nuclear spins observed in the experiment. This effect is discussed along with the recently obtained NMR results in the chain thallium sulfide and selenide.

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Section: Results Of the Experimentsmentioning

confidence: 93%

Section: Results Of the Experimentsmentioning

confidence: 99%

Indirect nuclear exchange coupling and electronic structure of the layered semiconductor TlS: NMR study and band structure calculation

Panich

Kashida

2004

J. Phys.: Condens. Matter

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“…Thus we would observe three lines with a 2:1:1 intensity ratio. We note that the observed chemical shifts of the Tl resonances are in the range of such shifts in the other Tl compounds [23][24][25][26][27][28][29][30][31][32][33][34], and that the obtained chemical shielding anisotropy is evidently caused by a nonspherical surrounding of Tl atom by six Se atoms, forming a non-spherical electronic shell of Tl.…”

Section: Thallium Nmr Spectra and Spin-lattice Relaxationmentioning

confidence: 89%

“…Since the chemical shift is angle dependent, one could generally observe four signals coming from two inequivalent Tl atoms in the first chain and from two inequivalent Tl atoms in the second (perpendicular) chain. However, due to the exchange interaction between Tl spins [23][24][25][26][27][28][29][30][31][32][33][34] two signals, whose chemical shifts are close to each other, collapse into one signal, revealing more intense line. Thus we would observe three lines with a 2:1:1 intensity ratio.…”

Section: Thallium Nmr Spectra and Spin-lattice Relaxationmentioning

confidence: 99%

Single-crystal NMR for the layered semiconductor TlGaSe₂

Panich

Kashida

2008

J. Phys.: Condens. Matter

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We report on a 69Ga and 205Tl NMR study of single-crystal thallium gallium selenide. Our findings show that transformation from the high temperature paraelectric phase to the low temperature ferroelectric phase occurs via an incommensurate phase that exists in the temperature range from Tc = 107.5 to Ti = 118 K. On approaching phase transition at Ti from above, the crystal exhibits soft mode behavior, which is somewhat different for thallium and gallium substructures. Redistribution of 69Ga line intensities with temperature in the ferroelectric phase indicates a variation of the domain structure of this phase.

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“…The extension of the results obtained t o the case of several non-equivalent systems of parallel chains will throughout this work be restricted by the TlHF2 structure [6]. All the spontaneous dipole moments are supposed t o be aligned along the chains, which in turn do not intersect and are directed along the four body diagonals of the cubic structure as shown in Fig.…”

Section: System Of Non-equivalent Chainsmentioning

confidence: 99%

Thermodynamic Features of the System of Packed Antiferroelectric Chains

Kholopov¹

1986

Physica Status Solidi (b)

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The system is considered of Ising-like chains suffering the antiferroelectric instability. The interaction between the chains is taken into account within the framework of the molecular field approximation. Then summing over states of a single chain is carried out by the method making immediately use of the fact, that the unit cell can consist of several atoms. Such an approach may sometimes be more convenient than the transfer-matrix method. An appropriate phase diagram in an uniform external field is investigated. As a result, the electrical effects essentially must be small so that the corresponding measurements will be difficult in such systems. As an example the TIHF? structure is discussed.

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One‐Dimensional Mechanism of Antiferroelectric Ordering in a Non‐Polar Crystal

Cited by 4 publications

References 4 publications

Indirect nuclear exchange coupling and electronic structure of the layered semiconductor TlS: NMR study and band structure calculation

Indirect nuclear exchange coupling and electronic structure of the layered semiconductor TlS: NMR study and band structure calculation

Single-crystal NMR for the layered semiconductor TlGaSe₂

Thermodynamic Features of the System of Packed Antiferroelectric Chains

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One‐Dimensional Mechanism of Antiferroelectric Ordering in a Non‐Polar Crystal

Cited by 4 publications

References 4 publications

Indirect nuclear exchange coupling and electronic structure of the layered semiconductor TlS: NMR study and band structure calculation

Indirect nuclear exchange coupling and electronic structure of the layered semiconductor TlS: NMR study and band structure calculation

Single-crystal NMR for the layered semiconductor TlGaSe2

Thermodynamic Features of the System of Packed Antiferroelectric Chains

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Product

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Single-crystal NMR for the layered semiconductor TlGaSe₂