Evidence for two spin-glass transitions with magnetoelastic and magnetoelectric couplings in the multiferroic (Bi1−x_{1-x}Bax_x)(Fe1−x_{1-x}Tix_x)O3_3 system

For disordered Heisenberg systems with small single ion anisotropy, two spin glass transitions below the long range ordered phase transition temperature has been predicted theoretically for compositions close to the percolation threshold. Experimental verification of these predictions is still controversial for conventional spin glasses. We show that multiferroic spin glass systems can provide a unique platform for verifying these theoretical predictions via a study of change in magnetoelastic and magnetoelectric couplings, obtained from an analysis of diffraction data, at the spin glass transition temperatures. Results of macroscopic and microscopic (x-ray and neutron scattering) measurements are presented on disordered BiFeO3, a canonical Heisenberg system with small single ion anisotropy, which reveal appearance of two spin glass phases SG1 and SG2 in coexistence with the LRO phase below the A-T and G-T lines. It is shown that the temperature dependence of the integrated intensity of the antiferromagnetic peak shows dips with respect to the Brillouin function behaviour around the SG1 and SG2 transition temperatures. The ferroelectric polarisation changes significantly at the two spin glass transition temperatures. These results, obtained using microscopic techniques, clearly demonstrate that the SG1 and SG2 transitions occur on the same magnetic sublattice and are intrinsic to the system. We also construct a phase diagram showing all the magnetic phases in BF-xBT system. While our results on the two spin glass transitions support the theoretical predictions, it also raises several open questions which need to be addressed by revisiting the existing theories of spin glass transitions by taking into account the effect of magnetoelastic and magnetoelectric couplings as well as electromagnons.Comment: 59 pages 21 figure

Stability of Lending Rate Stickiness: A Case Study of India

The paper postulates that in an environment of continuous financial reforms, the lending rate stickiness in an economy could be changing over the period. The financial reforms (of which deregulation of interest rates formed a major part) during the 1990s and the early 2000s and the changing role attributed to different policy rates during the reforms make India an interesting case study. The paper finds evidence of diminishing lending rate stickiness in case of India. During the major part of the study, Indian policymakers used the discount rate for policy signaling. The paper observes that as a result, the long-term rates like the lending rates did not react sufficiently to the changes in the short-term rates (e.g., repo rate) in this period unless the discount rate was also changed. Such behavior changed when policymakers started to use short-term rates like repo rates for policy signaling. Results in this paper suggest that when the impacts are added together, a change of 100 basis points in all policy rates towards the end of the reference period could change the lending rate in India almost by similar magnitude. These findings help to reconcile some of the contrasting findings on lending rate stickiness in case of India. Among possible factors still responsible for lending rate stickiness, the study identifies inelastic credit demand in India as an important factor. From policymaking perspective, however, it is postulated that as demand for personal and housing loans in India are likely to increase in future due to demographic factor, it is likely that such increase could tend to increase inflexibility in loan rates.Lending Rate Stickiness, Discount Rate Addiction, Monetary Policy Transmission

The Linearly Independent Non Orthogonal yet Energy Preserving (LINOEP) vectors

It is well known that, in any inner product space, a set of linearly independent (LI) vectors can be transformed to a set of orthogonal vectors, spanning the same space, by the Gram-Schmidt Orthogonalization Method (GSOM). In this paper, we propose a transformation from a set of LI vectors to a set of LI non orthogonal yet energy (square of the norm) preserving (LINOEP) vectors in an inner product space and we refer it as LINOEP method. We also show that there are various solutions to preserve the square of the norm.Comment: 6 pages, 2 figure

Intergrain connectivity and resistive broadening in vortex state: a comparison between MgB2, NbSe2 and Bi2Sr2Ca2Cu3O10 superconductors

Magnetoresistance and radio frequency penetration depth techniques are used to study grain connectivity and broadening of superconducting transition. We study and compare these issues in clean polycrytalline samples of three different superconducting systems e.g. MgB2, NbSe2 and Bi2Sr2Ca2Cu3O10. From the rf response, the bulk pinning force constant is evaluated. From high field transport measurements, H-T phase diagram is ascertained for the three systems with varying degrees of fluctuation and connectivity.Comment: Presented at the Applied Superconductivity Conference, Seattle (2006