Conduction electron spin resonance in the α-Yb1−xFexAlB4 (0 ⩽ x ⩽ 0.50) and α-LuAlB4 compounds. (5th June 2015)

• Record Type: Journal Article
• Authors: Holanda, L M; Lesseux, G G; Magnavita, E T; Ribeiro, R A; Nakatsuji, S; Kuga, K; Fisk, Z; Oseroff, S B; Urbano, R R; Rettori, C; Pagliuso, P G
• Is Part Of: Journal of physics. Volume 27:Number 25(2015)
• Publication Date: 2015-06-05
• Subjects: conduction electron spin resonance -- heavy fermions -- non-Fermi-liquid regime -- intermetallic compounds; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/0953-8984/27/25/255601
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: β -YbAlB4 has become one of the most studied heavy fermion systems since its discovery due to its remarkable physical properties. This system is the first reported Yb-based heavy-fermion superconductor (HFS) for which the low- T superconducting state emerges from a non-fermi-liquid (NFL) normal state associated with quantum criticality Nakatsuji et al 2008 Nature 4 603. Additionally, it presents a striking and unprecedented electron spin resonance (ESR) signal which behaves as a conduction electron spin resonance (CESR) at high temperatures and acquires features of the Yb 3+ local moment ESR at low temperatures. The latter, also named Kondo quasiparticles spin resonance (KQSR), has been defined as a 4 f - ce strongly coupled ESR mode that behaves as a local probe of the Kondo quasiparticles in a quantum critical regime, Holanda et al 2011 Phys. Rev. Lett. 107 026402 . Interestingly, β -YbAlB4 possesses a previously known structural variant, namely the α -YbAlB4, phase which is a paramagnetic Fermi liquid (FL) at low temperatures Macaluso et al 2007 Chem. Mater. 19 1918 . However, it has been recently suggested that the α -YbAlB4 phase may be tuned to NFL behavior and/or magnetic ordering as the compound is doped with Fe. Here we report ESR studies on the α -Yb1− x Fe x AlB4 (0 ⩽ x ⩽ 0.50) series as well as on the reference compound α -LuAlB4 . For all measured samples, the observed ESR signal behaves as a CESR in the entire temperature range (10 K ≲ T ≲ 300 K) in clear contrast with what has been observed for β -YbAlB4 . This striking result indicates that the proximity to a quantum critical point is crucial to the occurrence of a KQSR signal.