Quasideuteron configurations in odd-odd $N=Z$ nuclei

The isovector $M1\mathrm{}$ transitions between low-lying $T=1\mathrm{}$ and $T=0\mathrm{}$ states in odd-odd $N=Z$ nuclei are analyzed. Simple analytical expressions for $M1\mathrm{}$ transition strengths are derived within a single-$j$-shell approximation for both the $j=l+1/2\mathrm{}$ and $j=l-1/2$ cases. The large $B\left(M1\mathrm{}\right)\mathrm{}$ values for the $j=l+1/2\mathrm{}$ case are attributed to quasideuteron configurations. The $B\left(M1\mathrm{}\right)\mathrm{}$ values for the $j=l-1/2$ case are found to be small due to partial cancellation of spin and orbital parts of the $M1\mathrm{}$ matrix element.