A Comparative Study of Nonlinear Microwave Properties in ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7}$, TlBaCaCuO and HgBaCaCuO Microstrip Resonators

Microwave nonlinearity is investigated in several high-temperature superconductors (HTS) including YBa
₂
Cu
₃
O
₇
, TlBa
₂
CaCu
₂
O
₇
, Tl
₂
Ba
₂
CaCu
₂
O
₈
, TlBa
₂
Ca
₂
Cu
₃
O
₉
and HgBa
₂
CaCu
₂
O
_6+delta
microstrip resonators. The critical power
P

_c
, above which nonlinearity becomes a serious concern, was compared with the dc critical current density
J

_c
at temperatures above 77 K. When plotted at the real temperature scale,
Pc
and
J

_c
for each HTS system follow a similar trend near
T

_c
, indicating that a similar mechanism of magnetic pinning limits both
P

_c
and
J

_c
. This result suggests that a better
Pc
may be achieved in HTS films of enhanced magnetic pinning.