منابع مشابه
Purely Magnetic Spacetimes
Purely magnetic spacetimes, in which the Riemann tensor satisfies Rabcdu b u d = 0 for some unit timelike vector u, are studied. The algebraic consequences for the Weyl and Ricci tensors are examined in detail and consideration given to the uniqueness of u. Some remarks concerning the nature of the congruence associated with u are made. ∗ Email:[email protected]
متن کاملPurely Magnetic Spacetimes
Spacetimes in which the electric part of the Weyl tensor vanishes (relative to some timelike unit vector field) are said to be purely magnetic. Examples of purely magnetic spacetimes are known and are relatively easy to construct, if no restrictions are placed on the energy-momentum tensor. However it has long been conjectured that purely magnetic vacuum spacetimes (with or without a cosmologic...
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Imaging the magnetic fields around a non-magnetic impurity can provide a clear benchmark for quantifying the degree of magnetic frustration. Focusing on the strongly frustrated J1-J2 model and the spatially anisotropic J1a-J1b-J2 model, very distinct low energy behaviors reflect different levels of magnetic frustration. In the J1-J2 model, bound magnons appear trapped near the impurity in the g...
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ژورنال
عنوان ژورنال: Science
سال: 2013
ISSN: 0036-8075,1095-9203
DOI: 10.1126/science.340.6128.10-e