High-pressure ultrasonic study of the commensurate-incommensurate spin-density-wave transition in an antiferromagnetic Cr-0.3 at. % Ru alloy single crystal

Cankurtaran, Mustafa; Saunders, G. A.; Wang, Q; Ford, P. J.; Alberts, H. L.

doi:10.1103/physrevb.46.14370

Cited by 30 publications

(38 citation statements)

References 43 publications

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“…% Ru and Crϩ3.5 at. % Al the SDW was found [1][2][3] to couple strongly with the longitudinalmode acoustic phonons. Coupling with the shear-mode acoustic phonons is relatively weak.…”

Section: Introductionmentioning

confidence: 99%

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BOB Acoustic-mode vibrational anharmonicity in Cr-Si alloy single crystals

Prinsloo¹,

Alberts²,

Smit³

1997

Phys. Rev. B

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Measurements are reported of the hydrostatic-pressure dependences of the elastic constants of Crϩ0.5 at. % Si and Crϩ1.6 at. % Si alloy single crystals through the Néel transition. In the former crystal the Néel transition is a second-order incommensurate ͑I͒ spin-density-wave ͑SDW͒-to-paramagnetic ͑P͒ transition, while it is a first-order commensurate ͑C͒ SDW-to-P transition in the latter crystal. The pressure derivatives of the elastic constants at different constant temperatures are used to calculate the acoustic-mode Grüneisen parameters, which quantify the vibrational anharmonicity, as a function of temperature through the Néel transition of each crystal. For the Crϩ0.5 at. % Si crystal the mean long-wavelength acoustic mode Grüneisen parameter, ␥ el ϷϪ5, jumps by ⌬␥ el ϭ30, from ␥ el ϷϪ5 to ␥ el ϭϩ25, in going through the second-order ISDW-P Néel transition, and then decreases to a value of ␥ el Ϸϩ5 at temperatures well into the paramagnetic phase. This jump is much larger, ⌬␥ el ϭ170, from ␥ el ϭϪ50 to ␥ el ϭϩ150, in going through the first-order CSDW-P Néel transition of Crϩ1.6 at. % Si, after which ␥ el decreases to ␥ el Ϸ0 at temperatures deep into the paramagnetic phase. The results show very strong coupling of the SDW to the long-wavelength longitudinalacoustic phonons in both crystals. Coupling to the long-wavelength shear acoustic phonons is relatively weak. In both crystals there is also strong coupling of the longitudinal phonons with the spin fluctuations above T N . The present measurements are compared with anharmonic effects observed through the second-order CSDW-P Néel transitions of Crϩ0.3 at. % Ru and Crϩ3.5 at. % Al alloy single crystals.

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“…% Ru and Crϩ3.5 at. % Al the SDW was found [1][2][3] to couple strongly with the longitudinalmode acoustic phonons. Coupling with the shear-mode acoustic phonons is relatively weak.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3] Experimental studies of the vibrational anharmonicity were reported for Crϩ0.3 at. % Ru ͑Refs.…”

Section: Introductionmentioning

confidence: 99%

BOB Acoustic-mode vibrational anharmonicity in Cr-Si alloy single crystals

Prinsloo¹,

Alberts²,

Smit³

1997

Phys. Rev. B

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“…The acoustic-mode Grüneisen parameters, γ, of Cr and its alloys give information on the effects of the interactions between the SDW and the acoustic phonons on the vibrational anhar- monicity in the sample [2,3,13]. These parameters are obtained from ultrasonic wave velocity results as a function of applied hydrostatic pressure at constant temperature.…”

Section: Discussionmentioning

confidence: 99%

“…Amongst these are superconducting [5,6] properties for c > 17 at.% Ru, unusually large temperature and pressure derivatives of the magnetic phase transition temperatures for concentrations close to the triple point concentration [1,7] and unusual behaviour of the lattice anharmonicity in Cr 99.7 Ru 0.3 [2,3]. For Ru concentrations just above c t , of which c = 0.3 at.% Ru is a well studied example, the strong coupling between the CSDW and acoustic phonons gives [2,3] acoustic-mode softening with applied hydrostatic pressure and subsequently negative Grüneisen parameters. The question that arises is whether the unusual properties in the concentration range c t < c < 3 at.% Ru where the CSDW-P Néel transition temperature behaves with dT N /dc > 0, are also representative in the CSDW phase at higher concentrations, 3 < c < 17 at.% Ru, where the CSDW-P transition have an opposite behaviour, with dT N /dc < 0.…”

Section: Introductionmentioning

confidence: 97%

“…These diagrams show a triple point concentration where the commensurate (C) spin-density-wave (SDW), the incommensurate (I) SDW and the paramagnetic (P) phases coexist. The Cr-Ru system is a typical example of this family of Cr alloys that has been studied extensively [1][2][3][4], particularly for alloy concentrations around the triple point concentration c t = 0.16 at.% Ru [1]. For c < c t a Cr-Ru alloy remains in the ISDW phase at all 0 < T < T N and the transition at the Néel temperature (T N ) is an ISDW-P phase transition.…”

Section: Introductionmentioning

confidence: 99%

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