Ultrasonic investigation of the magnetic ordering in the quasi-one-dimensional S=1/2 antiferromagnet BaCu2Si2O7
Abstract
Magnetic ordering in the quasi-one-dimensional antiferromagnet BaCu2Si2O7 is investigated with ultrasonic waves propagating along the chain axis. Transverse waves are found to couple most strongly with the magnetic properties. This is observed through an important velocity softening below 140 K and a sharp stiffening in the ordered state at TN=9.2 K. We have mapped the H-T phase diagram by studying the stiffening anomaly in magnetic field oriented along the three crystal axes for values up to 8.5 T. The Néel temperature TN decreases the most with increasing magnetic field oriented along the easy axis c; for this configuration two exotic spin-flop states could be identified at 2.1 and 4.7 T. Along the b axis, TN decreases less with increasing field and a new phase transition is observed around 7.8 T. No field effects on TN or additional transitions could be detected along the a axis. These transitions are discussed in relation with previously reported scenarios concerning the magnetic order.
- Publication:
-
Physical Review B
- Pub Date:
- August 2002
- DOI:
- 10.1103/PhysRevB.66.054402
- Bibcode:
- 2002PhRvB..66e4402P
- Keywords:
-
- 75.30.Kz;
- 75.25.+z;
- 75.10.Jm;
- 75.50.Ee;
- Magnetic phase boundaries;
- Spin arrangements in magnetically ordered materials;
- Quantized spin models;
- Antiferromagnetics