Dresden 2003 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 19: Supraleitung: Elektronenstruktur, Phononen, Tunneln, Ordnungsparameter II

TT 19.6: Vortrag

Donnerstag, 27. März 2003, 15:45–16:00, HSZ301

Electronic Structure of ZrB₂ — •Eugenio Forzani, Dmitrij Bogdanov, and Klaus Winzer — I. Physikalisches Institut, Universität Göttingen, Bunsenstr.9 , 37073 Göttingen

The Fermi surface of ZrB₂ was studied with the de Haas - van Alphen (dHvA) effect. Several brances of dHvA frequencies were observed in the (1010)-, (0001)-, (1120)- plane. The measured cross section areas are in very good agreement with recent calculations of the Fermi surface of ZrB₂ [1]. For four orbits (є,µ,ν,ξ) with B^→ || c^→ and one orbit (ζ) with B^→ || a^→ a series of properties, i.e. the effective masses m^*, the Fermi velocities v_f and the Dingle temperatures T_D, were determined from the temperature and magnetic field dependence of the dHvA amplitudes. The comparison of the effective masses m^* with the orbit averaged calculated band masses m_b for the four orbits with B^→ || c^→ show that the electron - phonon coupling constant λ=(m^*/m_b)−1 of ZrB₂ is very small (|λ| ≤ 0,1). Hence,in view of the weak electron - phonon coupling the absence of superconductivity in our ZrB₂-single crystals (measured down to 50 mK) is readily understood.
Supported by the DFG under grant nr. Wi 549 / 5-1+2.

[1] H.Rosner et al.: Phys. Rev. B66, 024521 (2002)