Nonuniversal power law of the Hall scattering rate in a single-layer cuprateBi2Sr2−x

Abstract

In-plane resistivity, Hall coefficient, and magnetoresistance (MR) are measured in a series of highquality Bi2Sr2−xLaxCuO6 crystals with various carrier concentrations, from underdope to overdope. It is found that the temperature dependence of the Hall angle obeys a power law T α with α systematically decreasing with increasing doping, which questions the universality of the Fermi-liquid-like T 2 dependence of the "Hall scattering rate". The systematics of MR indicates an increasing role of spin scattering in underdoped samples.PACS numbers: 74.25. Fy, 74.62.Dh, 74.72.Hs The peculiar normal-state properties of high-T c cuprates are generally considered to be the keys to elucidate the high-T c mechanism, since they give us a clue to clarify the nature of the strongly-correlated electronic state of the cuprates. To understand the underlying electronic state of the cuprates, it is desirable to study the normal state at low temperatures [1] and to chase the systematic evolution thereof with carrier concentration [2]. Therefore, particularly useful system for the normalstate study is such a system where T c is relatively low and where the the carrier concentration can be changed in a wide range from underdope to overdope.A typical study in which a wide temperature window for the normal-state is desirable is the measurement of the temperature dependence of the scattering time. For example, the observation of the T -linear resistivity from 10 K to 700 K in Bi 2 Sr 2 CuO 6 (Bi-2201) [3] had a strong impact, because it clearly demonstrated the dominance of the electron-electron interaction in the scattering mechanism. In high-T c cuprates, it has been discussed that the charge transport is governed by two different scattering times with different temperature dependences [4][5][6]; according to this "two-scattering-time" model, in-plane resistivity ρ ab is governed by the transport scattering time τ tr (∼T −1 ) and the Hall angle θ H is governed by the "Hall scattering time" τ H (∼T −2 ). However, this idea of "scattering-time separation" has not yet gained a complete consensus and there are other approaches to understand the unusual normal-state transport properties [7,8]. Therefore, it would be useful to establish the temperature and doping range in which the T 2 behavior of the Hall scattering rate τ −1 H is observed. There are two widely-known cuprate systems which satisfy the requirements of the relatively low T c and the availability of a wide doping range; La 2−x Sr x CuO 4 (LSCO) system and Bi-2201 system. Bi-2201 has not been as intensively studied as LSCO, mostly because of the difficulty in obtaining high-quality single crystals. A number of problems have been known for Bi-2201 crystals: (a) the transport properties of B-2201 are quite non-reproducible even among crystals of nominally the same composition [9-11]; (b) the residual resistivity of the in-plane resistivity ρ ab is usually large (the smallest value reported to date is 70 µΩcm [3,11]), as opposed to LSCO, YBa 2 Cu 3 O 7 (YBCO), or Bi 2 Sr 2 CaCu 2...

From Kondo Effect to Fermi Liquid

“…The sign of R H is positive in hole-doped systems like YBa 2 Cu 3 O 7−δ (YBCO) and La 2−δ Sr δ CuO 4 (LSCO), whereas it is negative in electron-doped systems like Nd 2−δ Ce δ CuO 4 (NCCO), although their Fermi surfaces (FS's) observed in ARPES measurements are hole-like [25]. As for the MR, ∆ρ/ρ 0 ∝ T −4 holds for a wide range of temperatures [26,27]. Thus, the Kohler rule derived by a simple relaxation time approximation (RTA) in a single-band model, R H ∝const.…”

“…In this case we assign the d-orbit in the impurity model to a lattice point chosen arbitrarily in the periodic system. We can write the ground-state wave function Ψ g as (27). Here the conduction electrons are replaced by local electrons around the site 0 which do not include 0-site.…”

The normal state scattering rate in high- cuprates

“…In particular, the model is shown to provide a natural explanation for the non-universal power law behavior of cotΘ H (T ) observed in the Bi-based cuprates. 13,14 Finally, in section IV, justification arguments for this particular choice of scattering rate are presented and the implications of this phenomenological model for the physics of HTC across the phase diagram are discussed, with suggestions for future study. In the process, I challenge two of the previously established paradigms of the normal state in HTC; namely the linear low-T behavior of ρ ab (T ) and the relevance of the non-saturating ρ ab (T ) observed at higher temperatures.…”

Influence of doping level on the Hall coefficient and on the thermoelectric power inNd2−xCexCuO4+δ

“…If the quartic law is a universal law for electron-type band, one can consider the possibility to extract scattering rates for the two bands from the data of Hall angle. Another interesting idea is that one may link this change of Hall angle with the possible quantum critical point on the analogy of their hole-doped partners 19,25,26 . However, one difficulty is that the sign of Hall coefficient changes, and it is very hard to get the temperature dependent Hall angle around x = 0.15 ∼ 0.18.…”