Spin dynamics in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">La</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mi mathvariant="normal">−</mml:mi><mml:mi mathvariant="italic">x</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Sr</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="ital

Min

Physica Status Solidi (b)

et al. 2007

Electron spin resonance (ESR) spectra of La 1-x Pb x MnO 3 (0.1 ≤ x ≤ 0.5) compounds were recorded at different temperatures. Asymmetrical and distored resonance signals due to ferromagnetic correlations at temperatures T < T min became Lorentzian at T > T min , where T min is the temperature corresponding to the narrowest ESR linewidth. The ESR linewidth with respect to temperature, ∆H(T ), for the samples was fitted to the one-phonon process, ∆H(T ) = A + BT. We found that B decreased from 5.45 Oe/K for x = 0.1 to 4.61 Oe/K for x = 0.5, indicating the decrease of lattice distortions with the Pb addition. The temperature dependence of the ESR intensity, I(T ), for the samples was described well to an expression of I(T ) = I 0 exp (E a /k B T ). In the high-temperature region, 1/I(T ) obeyed the Curie -Weiss law.

Section: Original Papermentioning

confidence: 90%

ESR study of La_1–xPb_xMnO₃ (0.1 ≤ x ≤ 0.5) perovskites

Min

Physica Status Solidi (b)

et al. 2007

J. Phys.: Condens. Matter

“…Its relaxation occurs via the fast relaxing carriers. This is called bottleneck effect, which has indeed been observed in Mn 2+ doped La 2−x Sr x CuO 4 [57].…”

Section: Huge Oxygen-isotope Effect On the Charge Stripe Formationmentioning

confidence: 97%

Unconventional isotope effects in the high-temperature cuprate superconductors

Zhao

Keller

Conder

2001

139

We review various isotope effects in the high-Tc cuprate superconductors to assess the role of the electron-phonon interaction in the basic physics of these materials. Of particular interest are the unconventional isotope effects on the supercarrier mass, on the charge-stripe formation temperature, on the pseudogap formation temperature, on the EPR linewidth, on the spin-glass freezing temperature, and on the antiferromagnetic ordering temperature. The observed unconventional isotope effects strongly suggest that lattice vibrations play an important role in the microscopic pairing mechanism of high-temperature superconductivity.

J. Phys.: Condens. Matter

“…2(c) shows the variation of the integrated intensity as a function of temperature. We have tried to analyse the temperature dependence of intensity in terms of the bottleneck model 19,25 . In this picture, the EPR signal originates from both Mn 4+ and Mn 3+ ions and the intensity is proportional to the total susceptibility.…”

mentioning

confidence: 99%

An electron paramagnetic resonance study of Pr_0.6Ca_0.4MnO₃across the charge-ordering transition

Gupta¹,

Joshi²,

Bhat³

et al. 2000

We report the first electron paramagnetic resonance studies of single crystals and powders of Pr 0.6 Ca 0.4 MnO 3 in the 300-4.2 K range, covering the charge ordering transition at ∼ 240 K and antiferromagnetic transition (T N ) at ∼ 170 K. The asymmetry parameter for the Dysonian single crystal spectra shows anomalous increase at T co . Below T co the g-value increases continuously, suggesting a gradual strengthening of orbital ordering. The linewidth undergoes a sudden increase at T co and continues to increase down to T N .The intensity increases as the temperature is decreased till T co due to the renormalization of magnetic susceptibility arising from the build up of ferromagnetic correlations. The value of the exchange constant, J, is estimated to be 154 K.