| CURRENT PROJECT AT BAY 2 |
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| PI: |
E.D. Adams |
| Funding: |
NSF |
| Personnel: |
B-H. Eom, N. Masuhara |
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Properties of 3He in confined geometry are quite different from those of bulk. In the phase separated
3He clusters in hcp 4He solid matrix, Schrenk et al. reported a history-dependent maximum in the heat capacity at T ≈ 1 mK for pressures as low as 2.80 MPa. They suggested that this is a smooth continuation of the bulk solid magnetic ordering temperature TN, but they did not see the latent heat and much of the spin entropy remained at their lowest temperature. Matsunaga et al. reported a decrease of the magnetization around 1.05 mK for similar samples from 2.96 MPa to 3.06 MPa. They attributed this anomaly to a possible magnetic ordering in the nano-clusters different from that of the bulk in view of the strong field dependence.
In our previous report, we showed that the anomaly found in Matsunaga et al. is not a simple decrease of the magnetization. For example, in the pressure range where the anomaly occurred, the magnetization could be divided in to two components with different T2*’s. Only the component with long T2* shows an abnormal decrease of the magnetization and the results of Matsunaga et al. seem to be a mix of the two components. The long and short components showed antiferromagnetic and ferromagnetic behavior, respectively.
Currently we are investigating the specific heat to the temperatures in the range of 100 μK to see if there is an additional peak responsible for the “missing entropy” in the work of Schrenk et al..
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| References |
“NMR Characterization of 3He Nanoclusters Embedded in hcp 4He”,
B.-H. Eom, N. Masuhara, G.E. deGroot, J.S. Xia, and E.D. Adams, J. Low Temp. Phys.134, 631 (2004).
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"Magnetic properties of 3He nanoclusters embedded in HCP 4He",
B-H. Eom, V. A. Shvarts, N. Masuhara, J. S. Xia and E. D. Adams, Physica B 329, 396 (2003)
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"Novel Magnetism in 3He Nanoclusters",
N. Matsunaga, V.A. Shvarts, E.D. Adams, J.S. Xia, and E.A. Schuberth, Phys. Rev. Lett. 86, 2365 (2001)
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| EARLIER PROJECT AT BAY 2 (FINISHED) |
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| PI: |
M. W. Meisel |
| Funding: |
NSF |
| Personnel: |
N. Masuhara, B. Watson |
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The pairing energy 2Δ(T) of the Cooper pairs in superconductors and superfluids is a fundamental characteristic of these systems as all of their properties are linked to this energy scale. Since most of the experimentally accessible physical quantities are expressed in terms of the value of the energy gap at zero temperature Δ0, accurate measurements of this energy scale are desirable.
For the case of superfluid 3He, ultrasonic techniques are well suited to study 2Δ(P,T). However, conventional technique, temperature sweep at fixed frequency, does not work in the low temperature limit, where Δ(P, T) levels off. For this reason, we have been developing broadband technique and novel pulsed FT method. We have successfully measured Δ0 directly and found deviation from theories.
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| References |
"Direct measurement of the energy gap of superfluid 3He-B in the low temperature limit",
N. Masuhara, B. C. Watson, M. W. Meisel, Phys. Rev. Lett. 85, 2537 (2000)
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"Pulsed Fourier-transform ultrasonic spectroscopy for ultralow temperature applications",
N. Masuhara, B. C. Watson, M. W. Meisel, J. Low Temp. Phys. 121, 815 (2000)
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| EARLIER PROJECT AT BAY 2 (FINISHED) |
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| PI: |
M. W. Meisel |
| Funding: |
NSF |
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B. Watson, N. Masuhara, G. Granroth, G. G. Ihas |
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| References |
"Zero sound attenuation near the quantum limit in normal liquid 3He close to the superfluid transition",
B. C. Watson, N. Masuhara, M. W. Meisel, J. Low Temp. Phys. 130, 77 (2003)
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"Broadband frequency study of the zero sound attenuation near the quantum limit in normal liquid 3He close to the superfluid transition",
G. E. Granroth, N. Masuhara, G. G. Ihas, M. W. Meisel, J. Low Temp. Phys. 113, 543 (1998)
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| EARLIER PROJECT AT BAY 2 (FINISHED) |
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| PI: |
N. S. Sullivan |
| Funding: |
NSF |
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E. B. Genio , J-W. Xu, G. Granroth, G. G. Ihas |
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| References |
"Coupling of the nuclear spin alignment of quadrupolar nuclei to 3He at interfaces",
E. B. Genio, N. S. Sullivan, G. G. Ihas, J. Low Temp. Phys. 113, 323 (1998)
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"Ultra-low temperature thermometry using zeeman perturbed NQR",
E. B. Genio, G. G. Ihas, N. S. Sullivan, J. Low Temp. Phys. 110, 763 (1998)
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"Relaxation in powdered metallic antimony in contact with liquid 3He",
E. B. Genio, G. G. Ihas, N. S. Sullivan, J. Low Temp. Phys. 110, 369 (1998)
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"Nuclear spin coupling of 3He to metallic Sb at low temperatures",
E. B. Genio, J-W. Xu, N. S. Sullivan, G. G. Ihas, Chech. J. Low Temp. Phys. Suppl. l,46, 219 (1996)
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"Nuclear-Spin-Lattice Relaxation-times of Metallic Antimony at Low-temperatures",
E. B. Genio, J-W. Xu, T. Lang, G. G. Ihas, N. S. Sullivan, J. Low Temp. Phys. 101, 611 (1995)
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| EARLIER PROJECT AT BAY 2 (FINISHED) |
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| PI: |
M. W. Meisel |
| Funding: |
NSF |
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J-W. Xu, P.J.XC. Signore, B. Adnraka, W. Acree, Y. Takano |
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| References |
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"Low-Temperature Magnetic Susceptibility and Resistivity Measurements and Electron Probe Microanalysis of Y1-xUxPd3",
J. Xu, P.J.XC. Signore, B. Adnraka, W. Acree, M.W. Meisel, and Y. Takano, J. Alloys Comp., 216, 33 (1994)
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