One- and two-triplon spectra of a cuprate ladder.
We have performed inelastic neutron scattering on the near ideal spin-ladder compound La4Sr10Cu24O41 as a starting point for investigating doped ladders and their tendency toward superconductivity. A key feature was the separation of one-triplon and two-triplon scattering. Two-triplon scattering is observed quantitatively for the first time and so access is realized to the important strong magnetic quantum fluctuations. The spin gap is found to be 26.4+/-0.3 meV. The data are successfully modeled using the continuous unitary transformation method, and the exchange constants are determined by fitting to be Jleg=186 meV and Jrung=124 meV along the leg and rung, respectively; a substantial cyclic exchange of Jcyc=31 meV is confirmed.
Notbohm
S
S
Hahn-Meitner-Institut Berlin, Berlin, Germany.
Ribeiro
P
P
Lake
B
B
Tennant
D A
DA
Schmidt
K P
KP
Uhrig
G S
GS
Hess
C
C
Klingeler
R
R
Behr
G
G
Büchner
B
B
Reehuis
M
M
Bewley
R I
RI
Frost
C D
CD
Manuel
P
P
Eccleston
R S
RS