Contents
1 Introduction ................................................................... 1
1.1 Spin Ices ................................................................. 1
References ...................................................................... 8
2 Magnetic Monopoles in Spin Ices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1 Searches for Monopoles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.1.1 New Proposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
References ...................................................................... 18
3 Experiment .................................................................... 21
3.1 1K Cryostat .............................................................. 21
3.2 Spectrometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.2.1 External Noise Insulation of Spectrometer . . . . . . . . . . . . . . . . . . . . 25
3.2.2 Sample Preparation ............................................. 25
3.2.3 Recording Sample Spin Fluctuations .......................... 26
3.3 Initial Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.4 Monte Carlo Simulations ............................................... 27
3.5 Paradigm Shift from Resistor to Semiconductor . . . . . . . . . . . . . . . . . . . . . . . 30
References ...................................................................... 33
4 Plasma of Magnetic Monopoles ............................................. 35
4.1 Magnetic Monopole Generation and Recombination Noise........... 36
4.2 Variance of Monopole Pair Number Fluctuations ..................... 38
4.2.1 Variance for Monopole Number Fluctuations in
Dysprosium Titanate ............................................ 38
4.3 Predictions ............................................................... 39
4.4 Comparison with MC Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
References ...................................................................... 42
5 Analysis ........................................................................ 43
5.1 Analytic Structure of Noise ............................................. 43
5.2 Extraction of Time Constant ............................................ 44
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