Disappearance of Hall resistance in one-unit-cell-thickYBa2Cu3<

Abstract

Diagonal and Hall resistivities (pxx and pxy) in the normal and superconducting states are studied in one-unit-cell-thick YBa2Cu307-5 artificial materials. A number of transport properties in bulk YBa2Cu307-5 are shown to be inherent properties of the individual conducting Cu02 bilayers. Evidence of Kosterlitz-Thouless resistive transition as well as the excitation of free vortex and antivortex is presented.PACS numbers: 74.60.Ge, 74.70.Vy In high-temperature superconductors (HTS), twodimensional (2D) conducting Cu02 planes are weakly coupled by the Josephson effect and magnetic interactions. HTS show unusual transport properties in the normal state, such as T-linear-dependent resistivity and the r~'-dependent Hall resistivity [1,2]. It may be of importance for the study of pairing mechanisms to clarify whether these transport properties are intrinsic to the nature of a single 2D conducting layer or are a consequence of interlayer coupling. In addition, the problem of how the 2D superconducting sheets achieve the zero-resistance state has been a subject of much interest. Although the Kosterlitz-Thouless (KT) model [3][4][5] has been discussed for bulk samples [6-9], unknown interlayer coupling makes the interpretation ambiguous. Recently, superconducting transition has been shown to occur at finite temperatures in one-unit-cell-thick (l-UCT) YBCO [10]. It may be of decisive importance to clarify whether the superconducting transition in a single 2D CuOi layer is describable by KT theory.Here, we carry out detailed studies of diagonal and Hall resistivities, pxx and pxy, of l-UCT YBCO layers. The experimental results show that a number of physical properties of bulk YBCO are intrinsic to the individual Cu02 bilayers, being substantially unaffected by the interlayer coupling. We will show that, nevertheless, the temperature at which the resistance vanishes is remarkably suppressed in the absence of interlayer coupling. We present, for the first time, definite evidence of the occurrence of KT resistive transition in HTS. We study two types of samples, both epitaxially grown on the (100) surface of SrTiOs by the activated reactive evaporation method, in which the crystal growth is controlled on oneunit-cell scale through the observation of reflection highenergy electron diffraction (RHEED) oscillations [10]. The first type is l-UCT ultrathin films consisting of welldefined l-UCT layers of YBCO sandwiched by semiconducting 6-UCT PrBCO and 1 l-UCT PrBCO layers [Pr (6)/Y(l)/Pr(ll)] [10]. The second-type samples are YBCO/PrBCO superlattices, where a multiple layer of 1 -UCT YBCO and m-UCT PrBCO with m ==

Kosterlitz-Thouless-Type Transition in a Charge Ordered State of the Layered Organic Conductorα−(BEDT−TTF)2I3Uji1, Kodama2, Sugii3 et al. 2013Phys. Rev. Lett.Self Cite132190View full textAdd to dashboardCite

“…Because of the lnðrÞ binding potential, the I-V characteristics are expressed in the form V / I . This power law exponent exhibits jumplike behavior from 1 to 3 at T KT with decreasing temperature [7,[9][10][11]15]. Some other evidences of the KT transitions have also been reported [8][9][10]13,14]; however, the interpretation of these transitions is still controversial [12].…”

“…This power law exponent exhibits jumplike behavior from 1 to 3 at T KT with decreasing temperature [7,[9][10][11]15]. Some other evidences of the KT transitions have also been reported [8][9][10]13,14]; however, the interpretation of these transitions is still controversial [12].On the other hand, very few experimental studies have focused on 2D Coulomb gases except for those on Josephson junction arrays although the 2D Coulomb gas has been recognized as another example of a KT system [5]. The primary reason is the lack of relevant model materials; the Coulomb potential exhibits a three-dimensional (3D) form (1=r) in most materials.…”

“…After this theoretical prediction, this type of transition has been extensively investigated in various systems such as 2D XY spin systems [2][3][4], 2D electron gases [5], He 4 superfluids [6], layered (or thin film) superconductors [7][8][9][10][11][12][13][14][15], superconducting networks and Josephson junction arrays [16][17][18][19], and Dirac cone systems [20][21][22]. Above the transition temperature (T KT ), many unbound topological defects are thermally excited, but very few defects below T KT .…”

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

“…In this case, it has been suggested that the application of magnetic field tends to suppress the sign change. [17] As shown in Fig. 2, however, the sign change is not suppressed but enhanced by the application of magnetic field, and, moreover, R H is negative even in the normal state above T onset c for x = 0.10 and 0.11.…”

Hall coefficient ofLa1.88−yYySrSuzuki1, Goto2, Chiba3 et al. 2002Phys. Rev. B8190View full textAdd to dashboardCite

“…The reason is as follows: (a) In high-T c cuprates, the sign reversal of R H in the vortex states tends to vanish as increasing magnetic fields 26,27 . The data in this study is contrary to this tendency.…”