Melting of the orbital order in LaMnO3 probed by NMR

Article

关键词: JAHN-TELLER TRANSITION;    RELAXATION;    DISTORTION;   

DOI  :  10.1103/PhysRevB.87.125142

来源: SCIE

【 摘 要 】

The Mn spin correlations were studied near the O'-O phase transition at T-JT = 750 K up to 950 K with O-17 and La-139 NMR in a stoichiometric LaMnO3 crystalline sample. The measured local hyperfine fields originate from the electron density transferred from the e(g) and t(2g) orbitals to the 2s(O) and 6s(La) orbits, respectively. By probing the oxygen nuclei, we show that the correlations of the Mn spins are ferromagnetic in the ab plane and robust up to T-JT, whereas along the c axis they are antiferromagnetic and start to melt below T-JT, at about 550 K. Above T-JT, the ferromagnetic Mn-Mn exchange interaction is found isotropic. The room-temperature orbital mixing angle, phi(NMR) = 109 +/- 1.5 degrees, of the e(g) ground state is close to the reported value which was deduced from structural data on Jahn-Teller distorted MnO6 octahedra. For T > T-JT, LaMnO3 can be described in terms of nonpolarized e(g) orbitals since both e(g) orbitals are equally occupied. DOI: 10.1103/PhysRevB.87.125142

【 授权许可】

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