Magnetic Properties of the Bismuth Oxide α — Bi2<sub />O<sub>3</sub>

Kharkovskii, A.I.; Nizhankovskii, V.; Кравченко, Е. А.; Orlov, V. G.

doi:10.1515/zna-1996-5-649

Cited by 30 publications

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“…The SQUID-measurements of a-Bi 2 O 3 confirmed that it is not diamagnetic in the conventional sense [7,8]. The magnetization of a single crystal was positive at 4.2 K and highly anisotropic in magnetic fields H e up to 3j5 kOe [7].…”

Section: Introductionmentioning

confidence: 69%

“…Although the explanation implying H loc is consistent with the observed spectra, no unambiguous proof of either the origin of the magnetism or the mechanism of ordering the magnetic moments over a wide temperature range (in a-Bi 2 O 3 , it exceeds 400-) is available at the moment. The bismuth 6sp-valence electrons (most probably, an unshared electron pair) bearing the effective magnetic moment m eff $ 0.1m B [7,8] are capable of producing the hyperfine filed (õ50 G) of the same order as that estimated from the NQR spectra, which suggests the hyperfine nature of H loc . It is reasonable to think that the ordering of so small a m eff over such a wide temperature range results from the ordering of the electric dipole moments via strong coupling between the magnetic and electronic systems of the compounds.…”

Section: Discussionmentioning

confidence: 90%

“…The magnetization of a single crystal was positive at 4.2 K and highly anisotropic in magnetic fields H e up to 3j5 kOe [7]. Upon cooling the crystal in a magnetic field (FC), a dramatic increase of the magnetic moment of a-Bi 2 O 3 , compared to that upon cooling in zero field (ZFC), was observed as H e increased [8].…”

Section: Introductionmentioning

confidence: 99%

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Local Magnetic Fields in Some Bismuth-Based Diamagnets

et al. 2004

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Abstract. Evidence that local ordered magnetic fields from 30 to 250 G exist in bismuth-based diamagnetic compounds comprising neither d-nor f-elements was given by 209 Bi NQR spectroscopy and supported by SQUID measurements of a-Bi 2 O 3 . The NQR experiments involved a study of the zero-field line shapes, analysis of the Zeeman-perturbed patterns, and examination of the zero-field spin-echo envelopes in single crystals and powders. The results of the experiments followed by computer modeling of the observed spectra were interpreted assuming that ordered magnetic fields are located at the bismuth sites in a

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Section: Introductionmentioning

confidence: 69%

Section: Discussionmentioning

confidence: 90%

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Local Magnetic Fields in Some Bismuth-Based Diamagnets

et al. 2004

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“…Thus, according to the zerofield 2~ NQR data [1], supported by the resttlts of the SQUID measurements [10,11], a local magnetic field exists in ~t-Bi~O 3. As was mentioned above, the zero-fietd 2~ NQR spectrum of c~-Bi~O 3 appeared as typical Zeeman pattern: it displayed a quadruplet for vi and doublets for the lines of higher tran- SEE recorded for the v l transition in a powder Bi4Ge3012 sample is shown together with the split zero-field v l resonance given in the inset.…”

Section: Resultsmentioning

confidence: 96%

NQR indications of unconventional magnetism in some bismuth-based diamagnets

et al. 2004

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Ala evidence that local ordered magnetic fields from 30 to 200 G exist in diamagnets ct-Bi203, Bi304Br, Bi4Ge3Oi2, Bi2AI409 which comp¡ neither d-nor f-elements was earlier given by the zerofield and Zeeman-perturbed 2~ nuclear quadrupole resonance (NQR) spectra. With a view to fmd similar spectroscopic effects in other compotmds, we examined the 2~ NQR Zeeman-perturbed spectra of the Bi3BsO~2 oriented single crystal as well as the zero-field spin echo envelopes in Bi3B50~2 and Bi2Ge309. Distinctive modulations were displayed by the zero-field 2~ spin echo envelopes in Bi2Ge309 powder. The modeling of the spin echo envelopes within the density matrix formalism explained the observed effect by the presente of local ordered magnetic field of the order of 65 G at the Bi atoms. The zerofield modulations of the Z~ spin echo envelopes were also observed in Bi3B5OI2 indicating the presence of the internal source of line splitting. This finding and considerable deviation of the resonance intensity ratios from that in a pure NQR, found in the zero-field 2~ spectrum of the single crystal, were understood as indirect evidences that a local ordered magnetic field exists also in Bi3BsO12. The zero-field 2~ spin echo envelopes assigned to the lines split by the local magnetic fields in a-Bi203 and Bi4Ge3Ot2 were observed to display modulations on the appropriate curves.

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“…The existence of paramagnetic centers (holes in the unfilled p-electron shell of oxygen ions) was proposed as the origin of observed magnetoelectric effect in the α-Bi 2 O 3 single crystal [10]. The holes possess the magnetic moment due to spin and orbital magnetic moments.…”

Section: Discussionmentioning

confidence: 99%

Separation of quadrupole and magnetic mechanismsof ²⁰⁹Bi nuclear spin–lattice relaxation in Bi₄Ge₃O₁₂

Морозова

Gippius

Khozeev

et al. 2003

Physica Status Solidi (b)

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Bi NQR experiments. In the present paper the nuclear spin -lattice relaxation was studied in the Bi 4 Ge 3 O 12 single crystal by 209 Bi NQR spin -echo technique. The experimental relaxation curves were described by the single effective spin -lattice relaxation time T 1 . The temperature dependence of 1/T 1 was close to T n law with n = 2.4 -2.7. The nuclear spin -lattice relaxation in the multi-level system was theoretically calculated for the case of single-axial crystalline electric field. Both quadrupole and magnetic mechanisms of relaxation were taken into account. We conclude that the magnetic mechanism contributes noticeably to the spin -lattice relaxation in Bi 4 Ge 3 O 12 at T ≤ 50 K. 209 Bi NQR spectra of the Bi 4 Ge 3 O 12 single crystal in the presence of rather weak external dc-magnetic field (up to 500 Oe) [1]. The origin of these phenomena is not known yet. Therefore it is interesting to perform the 209 Bi NQR spin-lattice relaxation experiments on the Bi 4 Ge 3 O 12 single crystal to elucidate the nature of the relaxation mechanism (quadrupole or magnetic). IntroductionThe spin -lattice relaxation process in Bi 4 Ge 3 O 12 has to be described by the four relaxation times T 1i (i = 1, . . ., 4). For the quadrupole relaxation, T 1i depend on the quantities W 1 and W 2 , which are the coefficients in ∆m = ±1 and ∆m = ±2 relaxation transition probabilities [3]. The values and temperature dependences of W 1 and W 2 are governed by specific mechanism of quadrupole relaxation and are a priory unknown.Further problems arise when the magnetic mechanism competes with the quadrupole one in the spinlattice relaxation process [4][5][6]. The third unknown quantity W M , which is a coefficient in ∆m = ±1 magnetic relaxation transition probability [7], also affects the relaxation times T 1i in this case.

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Magnetic Properties of the Bismuth Oxide α — Bi2_O₃

Abstract: A very unusual magnetic behaviour of α - Bi

Cited by 30 publications

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Local Magnetic Fields in Some Bismuth-Based Diamagnets

Local Magnetic Fields in Some Bismuth-Based Diamagnets

NQR indications of unconventional magnetism in some bismuth-based diamagnets

Separation of quadrupole and magnetic mechanismsof ²⁰⁹Bi nuclear spin–lattice relaxation in Bi₄Ge₃O₁₂

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Magnetic Properties of the Bismuth Oxide α — Bi2O3

Abstract: A very unusual magnetic behaviour of α - Bi

Cited by 30 publications

References 0 publications

Local Magnetic Fields in Some Bismuth-Based Diamagnets

Local Magnetic Fields in Some Bismuth-Based Diamagnets

NQR indications of unconventional magnetism in some bismuth-based diamagnets

Separation of quadrupole and magnetic mechanismsof 209Bi nuclear spin–lattice relaxation in Bi4Ge3O12

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Magnetic Properties of the Bismuth Oxide α — Bi2_O₃

Separation of quadrupole and magnetic mechanismsof ²⁰⁹Bi nuclear spin–lattice relaxation in Bi₄Ge₃O₁₂