Peak effect inCeRu2:History dependence and supercooling

Abstract

We present experimental results on single crystal CeRu 2 showing that the extent of history dependence of peak-effect depends on the path followed in the space of field (H) and temperature ( T ). The (H,T) regime over which history effect is observed is larger if the vortex lattice is prepared by lowering T from above T C in constant H i.e. by field cooling. We compare this history effect with the very recently reported history dependence of peak-effect in detwinned single crystals of YBaCuO, highlighting the similarities and differences. We discuss the possibility of a first order vortex solid-solid transition in CeRu 2 within the realm of recent theoretical developments in the field of vortex matter.Typeset using REVT E X 1 Recent theoretical 1-4 and experimental 5-7 studies based on high T C superconductors (HTSC) suggest the existence of at least two distinctly resolved solid phases of vortex matter which are distinguished from the high-temperature high-field vortex liquid. These two vortex solid phases are referred to as low-field quasi-ordered solid or Bragg-glass and highfield disordered solid or vortex-glass (see Ref.8). The important question now is, what is the the order of the thermodynamic phase transitions (if any) between the various vortex phases?The Bragg-glass has long range order and it is expected to melt to vortex liquid at high temperature through a first order transition. Experimentally, the indication of a first order transition usually comes via a hysteretic behaviour of various properties, not necessarily thermodynamic ones. In HTSC samples also initial suggestions of a first order melting transition came via distinct hysteresis observed in transport property measurements 9-11 . The confirmatory tests of first order transition ofcourse involve the detection of discontinuous change in thermodynamic observables and the estimation of latent heat, and this has subsequently been achieved for vortex melting in HTSC materials through magnetization 12,13 and calorimetric measurements 14 . There also exists a less rigorous class of experimental tests which involves the study of phase co-existence and supercooling across a first order transtion. This kind of experiment has also come out to be pretty informative for the first order melting transition of the Bragg-glass in Bi 2 Sr 2 CaCu 2 O 8+δ (BSCCO) (Ref.15).With the establishment of the first order nature of the Bragg-glass to vortex liquid transition line, the focus in the recent years has shifted to the Bragg-glass to vortex-glass transition. In various HTSC materials peak-effect(PE) or fish-tail is used to track this field induced transition from Bragg-glass to vortex-glass, and this transition is obsereved to be a sharp transtion 5-7 . However, the exact nature of this transition -whether it is a continuous or a first order transition-is not established yet. Very recent magneto-optics studies on single crystal samples of BSCCO claim the presence of phase-coexistence 16,17 and supercooling 17 across the Bragg-glass-vortex-glass phase transiti...

Magnetic field induced enlargement of the regime of critical fluctuations in the classical superconductor V3Si from high-resolution specific heat experiments

“…This information may be essential for a detailed understanding of universal features observed in various type-II superconductors, especially the increasing width of the upper critical field line in magnetic fields [10,12,18,19] and eventually the peak effect, which has been reported to occur in direct vicinity to the regime where we observe strong fluctuations [20,[21][22][23][24]. Upon comparison of V 3 -1/2 = 0.006.…”

Investigations of the first order magnetic phase transition in dysprosium

“…The phase-coexistence (and hence the history effect) does not take place across a second order phase transition (SOPT). Through experiments, there have been a large number of reports providing successful demonstrations of subtle features associated with the FOPTs in many systems including manganites [3,4], other magnetically ordered compounds [5][6][7], superconductors [8][9][10], and shape memory alloys [11]. Recently, we have observed similar metastable characteristics across a FOPT in a dielectric system [12].…”

“…The envelope is so called (as we shall see below) because it represents the maximum hysteresis in the observed physical property. In contrast to this, the MHLs forms a powerful tool/technique to study the phenomenon of phase coexistence [4][5][6][7][8][9][10][11][12]. There are two kinds of MHLs.…”

“…There has been a sustained interest in the studies of phase-transitions [1,2] in several material systems in the past decade [3][4][5][6][7][8][9][10][11][12][13][14]. When the transition is of first order in nature, the property being measured close to the boundary of the transition normally exhibits what is referred to as the history effect.…”

Peak Effect in Superconductors: Absence of Phase Transition and Possibility of Jamming in Vortex Matter

“…The PE is found to be more pronounced in the weak pinning limit and progressively diminishes with increasing pinning strength [10,11]. An important characteristic of the PE phenomenon is the strong memory and history dependence of the various properties, and have been observed in static and dynamic experiments [12,13,14,15,16,17].…”