Internal magnetic field in La[sub 2[minus][ital x]]Sr[sub [ital x]]CuO[sub 4]:Gd observed by electron paramagnetic resonance

Journal Article · Thu Apr 01 00:00:00 EST 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.47.8156· OSTI ID:6657988

Rettori, C; Rao, D; Oseroff, S B ^[1]; Amoretti, G ^[2]; Fisk, Z ^[3]; Cheong, S ^[4]; Vier, D; Schultz, S ^[5]; Tovar, M; Zysler, R D ^[6]; Schirber, J E ^[7]

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1. Physics Department, San Diego State University, San Diego, California 92182 (United States)
2. Dipartimento di Fisica, Universita di Parma, I-43100 Parma (Italy)
3. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
4. AT T Bell Laboratories, Murray Hill, New Jersey 07974 (United States)
5. Physics Department, University of California, San Diego, California 92093 (United States)
6. Centro Atomico Bariloche and Instituto Balseiro, 8400 San Carlos de Bariloche, Rio Negro (Argentina)
7. Sandia National Laboratories, Albuquerque, New Mexico 87185-5800 (United States)

We have measured the electron paramagnetic resonance (EPR) of Gd[sup 3+] in single crystals of La[sub 2[minus][ital x]]Sr[sub [ital x]]CuO[sub 4+[delta]], as a function of temperature [ital T], magnetic-field angle, oxygen content, microwave frequency, and Sr concentration (0[le][ital x][le]0.024). For temperatures larger than the antiferromagnetic ordering temperature of the Cu lattice, [ital T][sub [ital N]], we have identified four different sites of Gd[sup 3+] as expected for twinned crystals and we are able to fit the data for all directions of the magnetic field. Samples annealed under vacuum or oxygen show only small changes on their crystal-field parameters and [ital g] values. For temperatures smaller than [ital T][sub [ital N]], the EPR lines are further split due to the internal magnetic field acting at the Gd site associated with the antiferromagnetic ordering of the Cu lattice. The temperature dependence of the splitting of the resonance lines allow us to calculate the moment per Cu ion. A value of [similar to]0.6[mu][sub [ital B]] per Cu ion at [ital T]=0 K is inferred, with the Cu moments lying in the [ital bc] plane about 5[degree] from the [ital c] axis. The data only can be fit for all the directions of the applied magnetic field if other mechanisms such as a Heisenberg type of exchange between the Cu and Gd moments or a distortion of the lattice below [ital T][sub [ital N]] are included.

• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6657988
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 47:13; ISSN 0163-1829
• Country of Publication: United States
• Language: English

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