Hall coefficient ofLa1.88−yYySr

Abstract

The Hall coefficient in the low-temperature tetragonal phase and the mid-temperature orthorhombic phase of La1.88−yYySr0.12CuO4 (y = 0, 0.04) single crystals is measured under high magnetic fields up to 9 T in order to investigate the detailed behavior of the transport properties at low temperatures in the stripe phase. When the superconductivity is suppressed by high magnetic fields, the Hall coefficient has negative values in low temperatures, and the temperature region of the negative values spreads as increasing magnetic fields. This result indicates that the Hall coefficient in the stripe phase around x = 0.12 is a finite negative value, not zero.Curious properties associated with "1/8-probrem" have been investigated over the last decade in the world and yet this is one of the centre of wide interest in high-T c superconductors. Let us begin this paper by reviewing something rather old. La 2−x Ba x CuO 4 (LBCO) and La 2−x Sr x CuO 4 (LSCO) show the local minimum of T c around x ∼ 0.12 1,2 . It has been predicted that the disappearance in LBCO or suppression in LSCO of the superconductivity is correlated with the structural change : the structural phase transition from the midtemperature orthorhombic phase (OMT, the space group Bmab) to the low-temperature tetragonal phase (TLT, the space group P4 2 /ncm) in LBCO and the precursor of the transition in LSCO around x = 0.12 3,4 . This prediction is verified by analysis of the crystal structure in Rare-earth doped LSCO system, which undergoes the structural phase transition to the TLT phase 5,6,7 . In addition to the disappearance or the suppression of the superconductivity, the two related phenomena appear in these system. One is magnetic order 8,9 , and the second is anomalous changes of transport properties, such as the Hall coefficient and the thermoelectric power 10,11 . It is suggested that the suppression of the superconductivity around x = 0.12 will be related with not only the crystal structure but also changes in magnetic and electronic states.The recent development on this problem is followed from the "stripe model" 12,13,14 . According to this model, the long-range modulated charge and spin ordering is stabilized in the TLT phase. Afterwards, magnetic superlattice peaks are observed by neutron diffraction in the orthorhombic superconducting phase La 1.88 Sr 0.12 CuO 4 single crystal, while no peaks associated with the charge ordering have been observed 15,16,17 . Notwithstanding no signal of the charge ordering by scattering technique, the magnetic order affects the character of the superconductivity in LSCO around18 . Therefore, a change in electronic states must appear more or less in case of the orthorhombic phase. It is necessary for full-understanding of this problem to discuss changes in the electronic state and in the crystal structure by investigating the detailed behavior of the transport properties of so-called stripe phase in the TLT phase and of the magnetically ordered state in the OMT phase. More recently, Noda et al. reported the temp...

Evidence for unusual superconducting correlations coexisting with stripe order inLa1.875Ba0.125CuO4

“…Without the yttrium in the crystal, R H of La 1.88 Sr 0.12 CuO 4 does not go negative for magnetic fields of 6 T or less, but it does go negative at T Ͻ 18 K for fields of 8 T and higher. 82 ͑Note that a negative R H was not observed in a study of LSCO films; 83 however, this may be due to the sensitivity of stripe correlations to strain effects.͒ The crossing of R H from positive to negative on cooling, as seen in crystals with known stripe order, has also been observed in underdoped YBa 2 Cu 3 O 6+x and YBa 2 Cu 4 O 8 samples that also exhibit quantum oscillations at sufficiently high magnetic fields. 84 [89][90][91] We note that it may also be important to take into account the unusual correlations in the stripe-ordered phase that we will discuss further on.…”

Competing charge, spin, and superconducting orders in underdopedYBa2Cu3Oy

“…19,20 A change from positive to negative Hall and Seebeck coefficients in YBCO around this doping region led to the interpretation that the Fermi pocket must have electron like character. [21][22][23][24][25] Negative Seebeck and Hall coefficients are also observed in La 1.8−x Eu 0.2 Sr x CuO 4 and several other La-based cuprates 23,24,[26][27][28][29][30][31] that are known to exhibit charge and spin-stripe order [7][8][9][32][33][34][35][36][37][38][39][40][41][42][43] . This strongly suggested that charge and/or spin order may exist in YBCO as well.…”

Hall coefficient in the ground state of stripe-ordered La2−xBaxCuOAdachi1, Kitajima2, Koike3 2011Phys. Rev. B10230View full textAdd to dashboardCite

“…[11]) and LSCO with x = 0.12 (Ref. [28]) where the spin stripe correlation is developed but the charge stripe order is not. Accordingly, it may be the case that R H becomes zero owing to the stabilization of the charge-spin stripe order at x = 1/8, while it becomes negative owing to the instability of the charge stripe order for x < 1/8.…”