Properties of La2CuO4 and related compounds

Cheong, Sang‐Wook; Thompson, J. D.; Fisk, Z.

doi:10.1016/0921-4534(89)90306-7

Cited by 119 publications

(26 citation statements)

References 102 publications

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“…The second entry is simply the first one rotated by 45° such that a direct comparison to the orthorhombic stoichiometric compound can be made. [47]. The Sr doped crystal was produced by Tanaka and Kojima using a travelling solvent/ floating zone system [48].…”

Section: Typical Resultsmentioning

confidence: 99%

Resonant ultrasound spectroscopic techniques for measurement of the elastic moduli of solids

Migliori

Sarrao

Visscher

et al. 1993

Physica B: Condensed Matter

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565

361

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The mechanical resonant response of a solid depends on its shape, density, elastic moduli and dissipation. We describe here instrumentation and computational methods for acquiring and analyzing the resonant ultrasound spectrum of very small (0.001 cm 3 ) samples as a function of temperature, and provide examples to demonstrate the power of the technique. The information acquired is in some cases comparable to that obtained from other more conventional ultrasonic measurement techniques, but one unique feature of resonant ultrasound spectroscopy (RUS) is that all moduli are determined simultaneously to very high accuracy. Thus in circumstances where high relative or absolute accuracy is required for very small crystalline or other anisotropic samples RUS can provide unique information. RUS is also sensitive to the fundamental symmetry of the object under test so that certain symmetry breaking effects are uniquely observable, and because transducers require neither couplant nor a flat surface, broken fragments of a material can be quickly screened for phase transitions and other temperature-dependent responses.

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Section: Typical Resultsmentioning

confidence: 99%

Resonant ultrasound spectroscopic techniques for measurement of the elastic moduli of solids

Migliori

Sarrao

Visscher

et al. 1993

Physica B: Condensed Matter

Self Cite

565

361

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“…62 Since in the LTO phase the critical field H c increases with decreasing T , at intermediate fields of ∼ 4 Tesla the spin-flip in La 2 CuO 4 at high temperatures has progressed to a higher degree than at low temperatures. 60 In contrast, at maximum field the DM moments in La 2 CuO 4 are ferromagnetically aligned down to 4 K (to the degree that is possible in a polycrystal 61 ). The susceptibility is smooth and increases monotonically with decreasing T and, moreover, is significantly larger than χ 2DHAF .…”

Section: Overview Of Sr and Eu Doping Dependencementioning

confidence: 99%

“…In contrast, in the LTT phase of the Eu-doped compound changes are rather weak. In the LTO phase, the influence of the field is particularly strong between 3 and 6 Tesla and follows from the first order spin-flip transition that can be induced for H c. 20,26,60,61 As is shown in Fig. 1 (a), at this transition the DM moments of adjacent CuO 2 planes, which are antiferromagnetically coupled in zero magnetic field, become ferromagnetically aligned.…”

Section: Overview Of Sr and Eu Doping Dependencementioning

confidence: 99%

Dzyaloshinsky-Moriya spin canting in the low-temperature tetragonal phase ofLa2−x−yEuySrx
Hücker
¹
,
Kataev
²
,
Pommer
³

et al. 2004
Phys. Rev. B

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The Cu spin magnetism in La2−x−yEuySrxCuO4 (x ≤ 0.17; y ≤ 0.2) has been studied by means of magnetization measurements in fields up to 14 Tesla. Our results clearly show that in the antiferromagnetic phase Dzyaloshinsky-Moriya (DM) superexchange causes Cu spin canting not only in the LTO phase but also in the structural low-temperature phases LTLO and LTT. In La1.8Eu0.2CuO4 the canted DM-moment is about 50% larger than in pure La2CuO4 which we attribute to the larger octahedral tilt angle in the Eu-doped compound. We also find clear evidence that the size of the canted DM-moment does not change significantly at the structural transition at TLT from LTO to LTLO and LTT. The most important change induced by the transition is a significant reduction of the magnetic coupling between the CuO2 planes. As a consequence, the spin-flip transition of the canted Cu spins which is observed in the LTO phase for magnetic field perpendicular to the CuO2 planes disappears in the LTT phase. The shape of the magnetization curves changes from the well known spin-flip type to a weak-ferromagnet type. However, no spontaneous weak ferromagnetism is observed even at very low temperatures, which seems to indicate that the interlayer decoupling in our samples is not perfect. Nonetheless, a small fraction ( 15%) of the DM-moments can be remanently magnetized throughout the entire antiferromagnetically ordered LTT/LTLO phase, i.e. for T < TLT and x < 0.02. It appears that the remanent DM-moment is perpendicular to the CuO2 planes. For magnetic field parallel to the CuO2 planes we find that the critical field of the spin-flop transition decreases in the LTLO phase, which might indicate a competition between different inplane anisotropies. To study the Cu spin magnetism in La2−x−yEuySrxCuO4, a careful analysis of the Van Vleck paramagnetism of the Eu 3+ ions was performed.

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“…A significant structural difference between La2CuO4 and the RE2CuO4 compounds is that Cu atoms are octahedrally coordinated by oxygens in La2CuO4, but in the RE2CuO4 materials, the coordination is square planar [ 4 ]. Electronically these two classes of CuO2-layer compounds also differ; Hall coefficient and thermoelectric power measurements on La2CuO4+6 suggest conduction by hole-like carriers, whereas, in RE2CuO4 the sign difference and magnitude of these effects imply a very small number of electron-like carriers [ 5 ]. Recently, Tokura et al [ 6 ] have found that substituting Ce into RE2_xCexCuO4, where RE = Pr, Nd and Sm, induces electron superconductivity with Tc ~ 20 K in these compounds which retain the I4/mmm structure of RE2CuO4 [ 7 ].…”

mentioning

confidence: 98%

Specific heat and anisotropic magnetic susceptibility of Pr2CuO4, Nd2CuO4 and Sm2CuO4 crystals

Hundley

Thompson

Cheong

et al. 1989

Physica C: Superconductivity

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117

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Properties of La2CuO4 and related compounds

Cited by 119 publications

References 102 publications

Resonant ultrasound spectroscopic techniques for measurement of the elastic moduli of solids

Resonant ultrasound spectroscopic techniques for measurement of the elastic moduli of solids

Dzyaloshinsky-Moriya spin canting in the low-temperature tetragonal phase ofLa2−x−yEuySrx
Hücker
¹
,
Kataev
²
,
Pommer
³

et al. 2004
Phys. Rev. B

Specific heat and anisotropic magnetic susceptibility of Pr2CuO4, Nd2CuO4 and Sm2CuO4 crystals

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Properties of La2CuO4 and related compounds

Cited by 119 publications

References 102 publications

Resonant ultrasound spectroscopic techniques for measurement of the elastic moduli of solids

Resonant ultrasound spectroscopic techniques for measurement of the elastic moduli of solids

Dzyaloshinsky-Moriya spin canting in the low-temperature tetragonal phase ofLa2−x−yEuySrxHücker1, Kataev2, Pommer3 et al. 2004Phys. Rev. B

Specific heat and anisotropic magnetic susceptibility of Pr2CuO4, Nd2CuO4 and Sm2CuO4 crystals

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Product

Resources

About

Dzyaloshinsky-Moriya spin canting in the low-temperature tetragonal phase ofLa2−x−yEuySrx
Hücker
¹
,
Kataev
²
,
Pommer
³

et al. 2004
Phys. Rev. B