Spin dynamics in oxide glass of Fe2O3–Bi2O3–B2O3 system

Akamatsu, Hirofumi; Tanaka, Katsuhisa; Fujita, Koji; Murai, Shinji

doi:10.1016/j.jmmm.2006.10.649

Cited by 13 publications

(18 citation statements)

References 11 publications

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“…1 For example, BiFeO 3 crystal exhibits an antiferromagnetic ͑AFM͒ transition at Néel temperature, T N = 643 K, with weak ferromagnetism 2 while rapidly quenched amorphous BiFeO 3 film exhibits a transition from a paramagnetic ͑PM͒ to spin-glass ͑SG͒ phase at the SG transition temperature, T SG =20 K. 3 The AFM superexchange interaction via oxide ions is predominant in most of the magnetic amorphous oxides. [4][5][6][7][8][9] Due to the randomly distributed magnetic ions in amorphous oxides, the predominant AFM interaction causes geometrical magnetic frustration in the arrangement of magnetic moments. This leads to the random freezing of magnetic moments, i.e., SG transition [4][5][6][7][8][9] and the drastic suppression of magnetic ordering temperature.…”

Section: Introductionmentioning

confidence: 99%

Impact of amorphization on the magnetic properties ofEuO-TiO2system

et al. 2010

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Recently, we have reported amorphization-induced ferromagnetism in a magnetic oxide; whereas crystalline EuTiO 3 is an antiferromagnet, its amorphous counterpart shows a ferromagnetic transition. In this paper, we have investigated the magnetic properties of amorphous EuO-TiO 2 system in detail. The present compounds, i.e., amorphous EuTiO 3 and Eu 2 TiO 4 , exhibit a paramagnetic-ferromagnetic transition followed by a spin-glass transition upon cooling down, thereby being characterized as reentrant ferromagnets. Interestingly, the magnetic ordering temperatures of amorphous EuTiO 3 and Eu 2 TiO 4 are comparable to and higher than those of their crystalline counterparts, respectively, indicating the enhancement of ferromagnetic interactions by amorphization. The origin of these features is discussed in terms of both the essential structural difference between amorphous and crystalline oxides and the magnetism unique to the crystalline EuO-TiO 2 compounds. We also find a correlation between the magnitude of ferromagnetic interactions and the covalency of Eu-O bonds.

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Section: Introductionmentioning

confidence: 99%

Impact of amorphization on the magnetic properties ofEuO-TiO2system

et al. 2010

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“…8 To clarify the mechanism of magnetic transition in oxide glasses, many studies have been performed on temperature dependence of dc and ac magnetic susceptibilities, Mössbauer spectrum, electron-spin-resonance spectrum, and so forth. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] As a result, magnetic oxide glasses, in particular, those containing 3d transition-metal ions, have been regarded as a prototype of insulating spin glass. Recently, we have reported that Fe 2 O 3 -TeO 2 glasses manifest curious phenomena relevant to spin dynamics, including magnetic aging and memory effects as well as critical slowing down similar to those observed in canonical spin glasses.…”

Section: Introductionmentioning

confidence: 99%

Magnetic properties of mixed-valence iron phosphate glasses

et al. 2009

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Magnetic properties of mixed-valence iron phosphate glasses, where there coexist Fe 2+ and Fe 3+ ions, have been investigated. The molar fraction of Fe 3+ with respect to the total iron ion, ͓Fe 3+ ͔ / ͓Fe total ͔, can be controlled by melting the glass at varied temperatures. Experiments of magnetic aging and memory effects as well as dynamic and static scaling analyses of relaxation time and nonlinear magnetic susceptibility have been performed to get insight into the nature of low-temperature magnetic phase of the glass system. The experimental results reveal that the iron phosphate glasses undergo paramagnet-spin-glass transitions at low temperatures. Temperature dependence of magnetic specific heat suggests that as the temperature is lowered, the magnetic moments start to be frozen at a temperature significantly higher than the spin-glass transition temperature accompanied by a deviation in magnetic susceptibility from Curie-Weiss law. The ratio of the absolute value of Weiss temperature to spin-glass transition temperature increases as the ratio ͓Fe 3+ ͔ / ͓Fe total ͔ becomes larger. This behavior is explainable in terms of the difference in single-ion anisotropy between Fe 3+ and Fe 2+ ions.

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“…1 Instead, short-range antiferromagnetic (AFM) superexchange interactions via 2p states of oxide ions are predominant in the magnetic oxide glasses, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] with some exceptions such as Eu 2+ -containing glasses, where ferromagnetic (FM) interactions prevail. [19][20][21][22][23] In a system where magnetic moments are located at randomly distributed cations, the short-range AFM interactions inevitably bring about magnetic frustrations of geometrical origin.…”

Section: Introductionmentioning

confidence: 99%

“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Those 3d TM-containing glasses have negative Weiss temperatures, the amplitude of which is tens or hundreds of degrees Kelvin, and exhibit a paramagnetic (PM) to SG transition at several or tens of degrees Kelvin. On the other hand, most of the oxide glasses possessing 4f rare-earth (RE) ions seldom show any magnetic transition down to 2 K, 24,25 which can be easily accessed in magnetic measurements.…”

Section: Introductionmentioning

confidence: 99%

Magnetic properties of oxide glasses containing iron and rare-earth ions

et al. 2011

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Measurements of fundamental magnetic properties including not only dc and ac susceptibilities but also magnetic aging effects have been performed for aluminoborate glasses with high concentrations of iron and rare-earth R 3+ ions (R = Sm, Gd, and Tb) in order to give an insight into the magnetic structures and interactions in amorphous oxides containing both 3d transition metal and 4f rare-earth ions, which manifest magnetic interactions that differ from each other. We demonstrate that the antiferromagnetic interactions between iron and rare-earth ions as well as those between iron ions play a significant role for their magnetic properties, while those between rare-earth ions are of little importance. Most of the rare-earth ions remain paramagnetic even below the spin-freezing temperatures under the strong molecular field caused by the spin-glass freezing of the iron ions, as in the case of rare-earth garnet ferrites.

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Spin dynamics in oxide glass of Fe2O3–Bi2O3–B2O3 system

Cited by 13 publications

References 11 publications

Impact of amorphization on the magnetic properties ofEuO-TiO2system

Impact of amorphization on the magnetic properties ofEuO-TiO2system

Magnetic properties of mixed-valence iron phosphate glasses

Magnetic properties of oxide glasses containing iron and rare-earth ions

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