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Articles **1** - **7** of ** 7**

## Full-Text Articles in Physics

Superspace Ward Identities In Supersymmetric Gauge Theories, Asim Gangopadhyaya, Darwin Chang

#### Superspace Ward Identities In Supersymmetric Gauge Theories, Asim Gangopadhyaya, Darwin Chang

*Physics: Faculty Publications and Other Works*

In superspace formulation of supersymmetric gauge theories, gauge invariance requires an infinite set of identities between the infinite set of renormalization constants. Using Ward identities in superspace, the same is derived. These identities at one loop level are also demonstrated.

Critical Behavior Of The One-Dimensional *S* = 1 *Xy* Model With Single-Ion Anisotropy, O. F. De Alcantara Bonfim, T. Schneider

#### Critical Behavior Of The One-Dimensional S = 1 Xy Model With Single-Ion Anisotropy, O. F. De Alcantara Bonfim, T. Schneider

*Physics Faculty Publications and Presentations*

We study the quantum critical behavior of the one-dimensional, *S *= 1 *XY* model in the presence of a single-ion anisotropy. Using a path-integral approach, we obtain, at *T* = 0 and for a positive anisotropy constant, a classical free-energy functional that allows discussion of the critical properties. The rescaling of frequencies is governed by the critical exponent *z* = 1. Renormalization-group arguments reveal that at criticality the system belongs to the same universality class as the isotropic 2-*d XY* model.

1/Σ Expansion For Quantum Percolation, A. Brooks Harris

#### 1/Σ Expansion For Quantum Percolation, A. Brooks Harris

*Department of Physics Papers*

A method for obtaining a 1/σ expansion for certain statistical models is presented, where σ+1 is the coordination number of the lattice. The method depends on being able to generate exact recursion relations for the Cayley tree. By perturbing the recursion relation to take account of the dominant loops in a hypercubic lattice for large σ, we obtain corrections of order σ^{−2} to the recursion relations. For the tight-binding model on random bond clusters (the quantum-percolation problem) we obtain corrections to this order for the critical concentration p^{*} at which the transition between localized and extended zero-energy ...

Scaling Approach To Spin-Glass Phenomena, S. E. Barnes, A. P. Malozemoff, B. Barbara

#### Scaling Approach To Spin-Glass Phenomena, S. E. Barnes, A. P. Malozemoff, B. Barbara

*Physics Articles and Papers*

The scaling model of spin-glass phenomena is extended to consider both longitudinal and transverse order parameters q_{1} and q_{t}. The lowest-order coupling in the free energy goes as q_{l}^{2}q_{t}^{2}. The field (h) dependence of the reduced temperature t for transverse freezing is found to be t∼h^{4/δ} where δ is the conventional nonlinear susceptibility field exponent (χ∼h^{2/δ}). While the transverse correlation length diverges at t=0, the longitudinal correlation length remains finite.

Esr And Magnetization Of The Spin-Glass Cumn At Low Concentrations, F. R. Hoekstra, G. J. Nieuwenhuys, K. Baberschke, S. E. Barnes

#### Esr And Magnetization Of The Spin-Glass Cumn At Low Concentrations, F. R. Hoekstra, G. J. Nieuwenhuys, K. Baberschke, S. E. Barnes

*Physics Articles and Papers*

We have determined the resonance frequency ω versus resonant field H diagram for CuMn with Mn concentrations 2, 3.5, and 5 at.%, both when H⃗ is parallel and antiparallel to the cooling field H⃗_{c}. From the parallel measurements we find anisotropy energy density constants K that are in agreement with K values determined from transverse susceptibility and torque measurements. However, the K values determined from the remanence reversal of dc magnetization are smaller by a factor of approximately 2. We suggest that this is caused by a breakdown of rigid-body spin rotations. By combining the parallel data with ...

Esr In Situ With A Josephson Tunnel Junction, K. Baberschke, K. D. Bures, S. E. Barnes

#### Esr In Situ With A Josephson Tunnel Junction, K. Baberschke, K. D. Bures, S. E. Barnes

*Physics Articles and Papers*

The in situ electron-spin resonance of a voltage-biased NbAuNb Josephson junction is reported. The Au barrier is doped with Gd or ^{167}Er ions. Sharp resonances appear in the I-V curves at frequencies equivalent to the crystal-field splitting of AuGd (1.0 and 1.7 GHz) and to the hyperfine splitting of Au^{167}Er (2.87 GHz). The principle of this new type of ESR-Josephson-junction spectrometer, as well as its application, is discussed.

Esr Relaxation In Spin Glasses, S. E. Barnes

#### Esr Relaxation In Spin Glasses, S. E. Barnes

*Physics Articles and Papers*

The Bloch-Hasegawa theory for the ESR of magnetic alloys is adapted and extended to spin glasses in the paramagnetic regime, that is, for temperatures T>T_{G}, the cusp temperature. Negative residual widths, reduced thermal broadening, and a possible critical divergence of the residual width are all explained in terms of minor extensions of the standard theory.