Investigation of the subharmonic structure on the current--voltage characteristic of a superconducting point contact
We investigated the subharmonic structure of the current--voltage (I--V) characteristics of superconducting Nb--Nb point contacts in an external microwave field of frequency 60--70 GHz. Distinct current ''substeps'' satisfying the generalized Josephson relation 2 eV/sub 0/= (n/m) h..omega../sub k/ (e is the electron charge, V/sub 0/ is the bias voltage, h is Planck's constant, ..omega../sub k/ is the frequency of the external microwave radiation, and n and m are integers) were observed at a temperature 4.2 K on the I--V characteristics of point contacts with large critical currents I/sub c/. The dependence of the amplitude of the substeps on the external radiationpower is investigated in detail. A theoretical model is proposed for the mechanism whereby the subharmonic structure is produced, and it is shown that allowance for the action of the contact radiation proper and of the harmonics of the external microwave field describes well the complicated character of the dependence of its amplitude on the microwave power. The model explains the ''gap subharmonics'' 2..delta../m and the ''gap harmonics'' n..delta.. observed on the I--V characteristics of tunnel junctions and point contacts in a zero external field.
- Research Organization:
- P. N. Lebedev Physics Institute, USSR Academy of Sciences
- OSTI ID:
- 5832080
- Journal Information:
- Sov. Phys. - JETP (Engl. Transl.); (United States), Journal Name: Sov. Phys. - JETP (Engl. Transl.); (United States) Vol. 49:2; ISSN SPHJA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Properties of low-resistivity superconducting niobium contacts
Investigation of bridge and tunnel contacts made from Nb/sub 3/Ge films
Related Subjects
360104 -- Metals & Alloys-- Physical Properties
420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ELECTRIC CONDUCTIVITY
ELECTRIC CONTACTS
ELECTRICAL EQUIPMENT
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
ELEMENTS
EQUIPMENT
FREQUENCY RANGE
GHZ RANGE
GHZ RANGE 01-100
HARMONICS
METALS
MICROWAVE RADIATION
NIOBIUM
OSCILLATIONS
PHYSICAL PROPERTIES
RADIATIONS
REFRACTORY METALS
SUPERCONDUCTING DEVICES
SUPERCONDUCTING JUNCTIONS
TRANSITION ELEMENTS
TUNNEL EFFECT