Microwave absorption by ortho-H2 pairs in solid hydrogen: temperature and density dependence of the frequencies

1980 ◽  
Vol 58 (9) ◽  
pp. 1356-1359 ◽  
Author(s):  
R. Jochemsen ◽  
B. W. Statt ◽  
W. N. Hardy
Keyword(s):  
Thermal Expansion ◽  
Specific Heat ◽  
Density Dependence ◽  
Energy Levels ◽  
Electric Quadrupole ◽  
Experimental Result ◽  
Para Hydrogen ◽  
Specific Heat Data ◽  
Helium Gas ◽  
Heat Data

The energy levels of an ortho-hydrogen pair in solid para-hydrogen are mainly determined by the electric quadrupole–quadrupole interaction between the ortho molecules which has an R−5 dependence. The frequencies of the observed absorption lines should therefore shift as a function of temperature due to thermal expansion. The experimental result for this shift, however, is a factor of 2 to 3 larger than that expected from thermal expansion calculated from specific heat data. We have also pressurized the sample at constant temperature with helium gas up to ≈0.4 bar, and obtained a confirmation of the R−5 dependence.

scholarly journals Thermal Expansion of Fe2MnSi

1988 ◽  
Vol 41 (6) ◽  
pp. 781 ◽  
Author(s):  
JR Miles ◽  
TF Smith ◽  
TR Finlayson
Keyword(s):  
Thermal Expansion ◽  
Curie Temperature ◽  
Specific Heat ◽  
Grüneisen Parameter ◽  
Specific Heat Data ◽  
Thermal Expansion Data ◽  
Narrow Peak ◽  
Temperature Range ◽  
Weak Anomaly ◽  
Heat Data

Measurements of the thermal expansion of FezMnSi in the temperature range 200-300 K are reported. A large, relatively narrow peak is found at the magnetic re-ordering temperature in contrast to a broad, weak anomaly at the Curie temperature. Values for the magnetic Gruneisen parameter 'Y m are derived from the thermal expansion data and previously reported specific heat data following the subtraction of a non-magnetic background.

Specific heat data of high-Tc superconductors: Lattice and electronic contributions

1989 ◽  
Vol 69 (6) ◽  
pp. 625-629 ◽  
Author(s):  
J.E. Gordon ◽  
M.L. Tan ◽  
R.A. Fisher ◽  
N.E. Phillips
Keyword(s):  
Specific Heat ◽  
High Tc Superconductors ◽  
Specific Heat Data ◽  
High Tc ◽  
Heat Data

Fast Dynamics in Glass-Formers: Relation to Fragility and the Kohlrausch Exponent

1996 ◽  
Vol 455 ◽  
Author(s):  
K. L. Ngai ◽  
C. M. Roland
Keyword(s):  
Relaxation Time ◽  
Low Temperature ◽  
Specific Heat ◽  
Raman Spectra ◽  
Low Temperatures ◽  
Coupling Model ◽  
Boson Peak ◽  
Specific Heat Data ◽  
Low Temperature Specific Heat ◽  
Heat Data

ABSTRACTFrom the Raman spectra and related inferences from low temperature specific heat data, Sokolov and coworkers have established that the ratio of the quasielastic and vibrational contributions at low temperatures (5∼10K) up to Tg correlates well with the degree of fragility and β of the glass-former. As pointed out by Sokolov (see his contribution in this Volume) such a correlation between the fast dynamics and structural a-relaxation at Tg(i.e., m and β) is intriguing, since at and below Tg, the α-relaxation time τα is more than twelve orders of magnitude longer than the quasielastic contribution and the boson peak. We show in this paper how the Coupling Model (CM) may provide an explanation for this correlation.

scholarly journals Magnetic studies of monoclinic Cu4O(SeO3)3, a copper-oxo-selenite derivative

2020 ◽  
Vol 233 ◽  
pp. 01002
Author(s):  
José F. Malta ◽  
Marta S.C. Henriques ◽  
José A. Paixão ◽  
António P. Gonçalves
Keyword(s):  
Low Temperature ◽  
Specific Heat ◽  
Intermediate Phase ◽  
Magnetic Transition ◽  
Chemical Vapour ◽  
Specific Heat Data ◽  
Magnetic Studies ◽  
Chemical Vapour Transport ◽  
Maximum Value ◽  
Heat Data

Cu4O(SeO3)3 is a copper-oxo-selenite belonging to the CuxO(SeO3)(x–1) family of the topological chiral magnet Cu2OSeO3. We report magnetometry and specific heat data measured in a monoclinic Cu4O(SeO3)3 single crystal grown through a Chemical Vapour Transport (CVT) reaction. Our study shows a typical antiferromagnetic behaviour, with a Néel temperature TN = 58 K, similar to that of the Cu2OSeO3 and an additional transition at 13 K. The effective magnetic moment per Cu atom is 1.84 μB, close to the expected theoretical value for Cu2+. The low-temperature M(H) curves, show a transition starting at Hc1 ~ 400 Oe at 1.8 K shifting to a lower value of ~ 280 Oe at 30 K, likely from a helical into a conical intermediate phase, and a second transition at Hc2 ~ 1 kOe, above which the net moment increases linearly with applied field. The magnetisation moment value in a 90 kOe field is 0.053 μB/Cu at 1.8 K and attains a maximum value of 0.061 μB at 13 K. Low-temperature specific heat measurements confirm the presence of the magnetic transition at 13 K, slightly shifting to lower temperatures under an applied magnetic field.

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