Abstract
The magnetically induced phase transitions, near the tricritical point of FeCl2 were studied by acoustic velocity measurements. Longitudinal waves propagating along the (100) trigonal axis exhibit a critical shift in the velocity along the second order λ-line and anomalous change at the first order phase transitions. The phase diagram in the plane of temperature and applied magnetic field is constructed near the tricritical point.
| Original language | English |
|---|---|
| Pages (from-to) | 1129-1131 |
| Number of pages | 3 |
| Journal | Solid State Communications |
| Volume | 25 |
| Issue number | 12 |
| DOIs | |
| State | Published - Mar 1978 |
| Externally published | Yes |
Bibliographical note
Funding Information:THE COUPLING of sound waves to critical fluctuations near phase transitions, gives rise to a pronounced attenuation and velocity shift \[1\].These phenomena have phase transitions. Here we report on the observation of a critical softening of the elastic stiffness near the tricitical point of a metamagnetic FeC! 2 \[2—9\]F.eC12 is an antiferromagnet with a layered type spin structure. Thereisa2~feiorrnosma,nadgnaenticaenxticfhearrnogmeaJ1gnbeettiwceeexnchtahnege. ~2 planebetweenFeadjacent planes, that is about twenty times weaker than .11. The magnetic moments are aligned by a relatively high anisotropy perpendicular to the Fe2~ layers and along the trigonal axis of the crystal. It has been found that below the tricritical temperature —21 K under an increasing applied magnetic field ~ the crystal undergoes a first order transition to a paramagnetic state. The transition is at constant internal field and over a range of~ and during the transition the crystal is a mixture of para-and antiferromagnetic domains. Above T~the transition from the antiferromagnetic phase to the paramagnetic phase is of second-order type. The magnetic phase diagram of FeCl 2 has been * This work was supported in part by the U.S.—Israel Binational Science Foundation through Research Grant No. 452. t Present address: Center for Materials Science and Engineering Massachusetts Institute of Technology, Cambridge.
Funding
THE COUPLING of sound waves to critical fluctuations near phase transitions, gives rise to a pronounced attenuation and velocity shift \[1\].These phenomena have phase transitions. Here we report on the observation of a critical softening of the elastic stiffness near the tricitical point of a metamagnetic FeC! 2 \[2—9\]F.eC12 is an antiferromagnet with a layered type spin structure. Thereisa2~feiorrnosma,nadgnaenticaenxticfhearrnogmeaJ1gnbeettiwceeexnchtahnege. ~2 planebetweenFeadjacent planes, that is about twenty times weaker than .11. The magnetic moments are aligned by a relatively high anisotropy perpendicular to the Fe2~ layers and along the trigonal axis of the crystal. It has been found that below the tricritical temperature —21 K under an increasing applied magnetic field ~ the crystal undergoes a first order transition to a paramagnetic state. The transition is at constant internal field and over a range of~ and during the transition the crystal is a mixture of para-and antiferromagnetic domains. Above T~the transition from the antiferromagnetic phase to the paramagnetic phase is of second-order type. The magnetic phase diagram of FeCl 2 has been * This work was supported in part by the U.S.—Israel Binational Science Foundation through Research Grant No. 452. t Present address: Center for Materials Science and Engineering Massachusetts Institute of Technology, Cambridge.
| Funders | Funder number |
|---|---|
| United States-Israel Binational Science Foundation | 452 |