Electronic structure of layered manganite La 1.1 Sr 1.9 Mn 2 O 7 studied by angle-resolved photoemission spectroscopy at low temperatures

Abstract

To clarify an electronic structure of an layered manganite, we have performed angle-resolved photoemission spectroscopy on La 2−2 x Sr 1+2 x Mn 2 O 7 ( x = 0.45 ), in which a phase transition occurs from an antiferromagnetic insulating phase to a canted antiferromagnetic metallic phase at 95 K. A spectral weight at the Fermi level is suppressed at 10 K, which is in contrast with the findings that a finite spectral weight exists for x = 0.40 [N. Mannella, W. Yang, X.J. Zhou, H. Zheng, J.F. Mitchell, J. Zaanen, T.P. Devereaux, N. Nagaosa, Z. Hussain, Z.-X. Shen, Nature (London) 438 (2005) 474; Z. Sun, Y.-D. Chuang, A.V. Fedorov, J.F. Douglas, D. Reznik, F. Weber, N. Aliouane, D.N. Argyriou, H. Zheng, J.F. Mitchell, T. Kimura, Y. Tokura, A. Revcolevschi, D.S. Dessau, Phys. Rev. Lett. 97 (2006) 056401; Y.-D. Chuang, et al., Science 292 (2001) 1509]. On the other hand, the mapping of the spectral weight in the vicinity of the Fermi level possesses a rather straight part in the Brillouin zone. This is a common feature of an electronic structure in a wide hole concentration range of the La 2−2 x Sr 1+2 x Mn 2 O 7 system, which is independent of a magnetic structure.