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August 11
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Aug. 11 - 5a
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11:00 - 11:30
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11:30 - 12:00
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12:00 - 12:30
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| Kondo Problems in Quantum Critical Environments |
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Hideaki Maebashi |
| The asymptotic low temperature singularities in the thermodynamic and transport properties of many solids appear to be due to impurities. While several impurity models have quantum critical points (QCP's), where such singularities may be expected, they require special symmetries unlikely to be present in real systems. An alternate possibility is that the environment around the impurities is near a QCP, so that singular low energy fluctuations are present. We investigate the problem which couples such fluctuations of the quantum critical environment to the quantum fluctuation or Kondo effect of ordinary spin-1/2 magnetic impurities (not requiring any special symmetries) [1,2]. We show that the problem maps onto a multichannel problem. A variety of fixed points is discovered asymptotically near the QCP. Among these is a new variety of stable fixed point of a multichannel Kondo problem which does not require any channel symmetries. At this point Kondo screening disappears but coupling to the critical spin fluctuations remains. Besides its intrinsic interest, the problem is an essential ingredient in the problem of antiferromagnetic QCP's in heavy fermions. [1] H. Maebashi, K. Miyake, and C.M. Varma, Phys. Rev. Lett. 88 (2002) 226403. [2] H. Maebashi, K. Miyake, and C.M. Varma, Phys. Rev. Lett. 95 (2005) 207207. |