Abstract
In the ground state of Ho2Ti2O7 spin ice, the disorder of the magnetic moments follows the same rules as the proton disorder in water ice. Excitations take the form of magnetic monopoles that interact via a magnetic Coulomb interaction. Muon spin rotation has been used to probe the low-temperature magnetic behaviour in single crystal Ho2−xYxTi2O7 (x = 0, 0.1, 1, 1.6 and 2). At very low temperatures, a linear field dependence for the relaxation rate of the muon precession λ(B), that in some previous experiments on Dy2Ti2O7 spin ice has been associated with monopole currents, is observed in samples with x = 0, and 0.1. A signal from the magnetic fields penetrating into the silver sample plate due to the magnetization of the crystals is observed for all the samples containing Ho allowing us to study the unusual magnetic dynamics of Y doped spin ice.
Highlights
In the ground state of Ho2Ti2O7 spin ice, the disorder of the magnetic moments follows the same rules as the proton disorder in water ice
A signal from the magnetic fields penetrating into the silver sample plate due to the magnetization of the crystals is observed for all the samples containing Ho allowing us to study the unusual magnetic dynamics of
For two samples (x 5 0.1 and 1.6) we collected fieldcooled-cooling data. In both cases a divergence between the zerofield-cooled warming (ZFCW) and the field-cooled cooling (FCC) curves appears at TCR
Summary
In the ground state of Ho2Ti2O7 spin ice, the disorder of the magnetic moments follows the same rules as the proton disorder in water ice. A linear field dependence for the relaxation rate of the muon precession l(B), that in some previous experiments on Dy2Ti2O7 spin ice has been associated with monopole currents, is observed in samples with x 5 0, and 0.1. Bramwell et al used transverse-field muon spin-rotation (TF-mSR) to investigate the magnitude and dynamics of the magnetic charge in Dy2Ti2O7 spin ice[14]. 16,18,19 If this is the case it is difficult to understand how the fields of 1–2 mT used in Ref. 14 could lead to a precession signal Both Dunsiger et al.[16] and later Blundell[19] have suggested that the signals seen in the mSR data in Ref. 14 originate from outside the sample. T . 0.07 K) cannot be explained by exterior muons and that the Wien effect signal originates from muons within the sample or muons sufficiently close to the surface of the sample so as to probe the monopolar far field
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