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Title: The effect of pressure on the heavy-electron superconductors UBe sub 13 and URu sub 2 Si sub 2

Thesis/Dissertation ·
OSTI ID:5216109

A study of the pressure dependence of the normal-state properties of the heavy-electron superconductors UBe{sub 13} and URu{sub 2}Si{sub 2} was undertaken in order to explore the relationship of Kondo lattice properties to the properties expected for dilute Kondo systems. The compounds UBe{sub 13} was the second heavy-electron superconductor identified, having a superconducting transition temperature 0.97 K and an electronic specific heat coefficient of 1100 mJ/mole-K{sup 2}. The electrical resistivity {rho}(T) was measured at pressures to 152 kbar showing two rates of increase in the temperature of the {rho} maximum T, one rate of 0.25 K/kbar below {approximately} 30 kbar and a second rate of 0.65 K/kbar above {approximately} 30 kbar. At low temperatures {rho}(T) increases quadratically with temperature T, with the T range increasing from less than 1 K at 1 bar to over 16.5 K at 150 kbar. The compound URu{sub 2}Si{sub 2} exhibits two electronic phase transitions: superconductivity at T{sub c} 1.5 K and an itinerant antiferromagnetic transition at T{sub o} 17.5 K. From pressure-dependent resistivity {rho}(T) measurements to 15.4 kbar the effect of pressure was shown to decrease T{sub c} at a rate of {minus}95 mK/kbar and increase T{sub o} at a rate of 130 mK/kbar below 12 kbar and at a higher rate at pressures.

Research Organization:
California Univ., San Diego, CA (USA)
OSTI ID:
5216109
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English