Exploring the effect of hole localization on the charge–phonon dynamics of hole doped delafossite. (10th August 2017)

• Record Type: Journal Article
• Authors: Mazumder, Nilesh; Mandal, Prasanta; Roy, Rajarshi; Ghorai, Uttam Kumar; Saha, Subhajit; Chattopadhyay, Kalyan Kumar
• Is Part Of: Journal of physics. Volume 29:Number 37(2017)
• Publication Date: 2017-08-10
• Subjects: Raman spectroscopy -- hole doping -- charge–phonon interaction -- delocalization processes; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/aa7cb2
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: For weak or moderate doping, electrical measurement is not suitable for detecting changes in the charge localization inside a semiconductor. Here, to investigate the nature of charge–phonon coupling in the presence of gradually delocalized holes within a weak doping regime (~10 16 cm −3 ), we examine the temperature dependent Raman spectra (303–817 K) of prototype hole doped delafossite C u C r 1 − x M g x O 2 − y S y ( x = 0/0.03, y = 0/0.01). For both E g and A 1 g phonons, negative lineshape asymmetry and relative thermal hardening are distinctly observed upon S O × and ( M g C r + S O × ) doping. Using Allen formalism, charge density of states at the Fermi level per spin and molecule, and charge delocalization associated to a − b plane, are estimated to increase appreciably upon codoping compared to the c -axis. We delineate the interdependence between charge–phonon coupling constant ( λ ) and anharmonic phonon lifetime ( τ a n h ), and deduce that excitation of delocalized holes weakly coupled with phonons of larger τ a n h is the governing feature of observed Fano asymmetry ( q ) reversal.