de Haas-van Alphen Studies of YbAs above and below Néel Temperature

Magnetotransport and electronic structure of the antiferromagnetic semimetal YbAs

“…Moreover, to gain insight into effect of correlations as well as the topology of the band structure, the Fermi surfaces and carrier effective masses were investigated via angle dependent SdH oscillations, ARPES measurements and DFT calculations. SdH oscillations reveal five Fermi surfaces pockets, one more than previous studies [39], and an analysis of the temperature dependence of the SdH amplitudes above T N shows that the charge carriers of all pockets have light effective masses. Meanwhile, no evidence for a Kondo resonance was found from ARPES measurements down to 10 K, and the results are in good agreement with DFT calculations assuming well localized 4f -electrons.…”

“…On the other hand, the resistivity ρ(T ) shows metallic behavior, without a logarithmic temperature dependence or Kondo coherence peak [38], and the carrier concentration n ∼ 10 20 cm −3 is only about 1% of the magnetic Yb-ions, which is far less than that required for full Kondo screening [38]. A de Haas-van Alphen (dHvA) effect study revealed the presence of three ellipsoidal electron pockets and one spherical hole pocket, where the charge carriers all have rather small effective masses [39].…”

“…Various scenarios have been proposed to account for the seemingly contradictory experimental results [36,38,[40][41][42][43][44], among which the p-f mixing model has been widely discussed [38][39][40]45]. In this scenario, the hole states become heavy, but the electrons remain light and mobile, and therefore the metallic behavior of ρ(T ) is explained by electrons dominating the transport properties, while the additional hole pockets not detected in previous dHvA studies are expected to have large effective charge carrier masses, accounting for the greatly enhanced Sommerfeld coefficient [39,45]. On the other hand, inelastic neutron scattering (INS) measurements reveal the development of short-range spin correlations below around 20 K [46,47], which may also explain the reduced magnetic entropy at T N , which is gradually released up to 20 K where the spin correlations disappear.…”

Chapter 241 The Dual, Localized or Band‐Like, Character of the 4f‐States

“…Experimentally, the position of the f 14 band is found $0.2 eV above the Fermi level in YbN, YbP, andYbAs (Degiorgi et al, 1990, 1993). Other experiments have revealed heavy-electron behaviour in Yb pnictides (Ott et al, 1985;Sakon et al, 1992;Takeda et al, 1993), but this can be a reflection of sample non-stoichiometry (Degiorgi et al, 1990(Degiorgi et al, , 1993. The discrepancy between the present electronic structure and the picture provided by Degiorgi et al (1990Degiorgi et al ( , 1993 can be due to the LSD approximation, since the position of the narrow f 14 band in the theory is solely determined by the LSD potential (no correlation correction).…”

High Quality Single-Crystal Growth and De Haas–Van Alphen Measurements of YbAl2

“…As for Yb-based compounds, the previous dHvA studies were mainly done to Pauli paramagnets such as YbIn 3 , YbSn 3 , YbGa 2 , YbBi 2 and YbZn 11 , where Yb-valence is divalent [2][3][4][5][6][7]. Recently, there are few dHvA reports for such an intermediate valence system and a heavy-fermion system, such as YbAs, YbAl 3 , -YbAlB 4 , YbCu 2 Si 2 , and YbRh 2 Si 2 [8][9][10][11][12]. However, the several results of dHvA measurements were still not much in agreement with their theoretical calculations [9,10,12].…”