1M.Rotter „Magnetostriction“ Course Lorena 2007

New Topics

• Fe-Ga• Magnetic Shape Memory Effect• Gd Compounds, Gd-Si• RE Metals Sm, Tm• MEP

2M.Rotter „Magnetostriction“ Course Lorena 2007

FeGa ?

Lattice parameter plots of solute element content in Fe: (   ) Fe–Al alloys, (  ) Fe–Be alloys, and (×) Fe–Ga alloys

Magnetostriction curves of (a) Fe–15 at. % Ga, directionally cast (DS) and heat treated at 600 °C for 1 h and (b) Fe–15 at. % Ga–5 at. % Al, directionally cast (DS) and heat treated at 1100 °C for 1 h and 730 °C for 1 h

N. Srisukhumbowornchai and S. Guruswamy Journal of Applied Physics 90( 2001) 5680

3M.Rotter „Magnetostriction“ Course Lorena 2007

4M.Rotter „Magnetostriction“ Course Lorena 2007

0 1 2 3 4 50

30

60

90

120

Fe0.725

Ga0.275

l /

l (p

pm

)

0H (T)

AS CAST 150 K 280 K

HT: 1100oC/1h + 875 oC/1h 150 K 280 K

R. Grössinger, R. Sato, H. Müller, S. Heiss, 2006

5M.Rotter „Magnetostriction“ Course Lorena 2007

Magnetic Shape Memory Effect

Principle of magnetic field induced re-orientation of martensitic variants.

Ferromagnetic shape memory alloys (FSMA) are smart materials possessing not only ferromagnetic as well as thermal shape memory properties but also large magnetic field induced strains. In single crystalline Ni2MnGa bulk material, strains as large as 10% have been realized. 

6M.Rotter „Magnetostriction“ Course Lorena 2007

Gd5(SixGe1-x)4

Morellon et. al. 2000

Morellon et. al. 2000

O(II)O(I)

TN= 127 KTC= 81 K

7M.Rotter „Magnetostriction“ Course Lorena 2007

Samarium

0 5 10 15 20 25 30 35 40

0,00

0,05

0,10

0,15 <1120> 4.2 K <0001> 4.2 K <0001> 20.4 K

Sm

M ( B

/ato

m)

0H (T)

K. McEwen et al. J. Phys. F: Metal Phys.4 (1974) 2264

Magnetization

8M.Rotter „Magnetostriction“ Course Lorena 2007

0 50 100 150 200 250 300-2,0x10-3

0,0

2,0x10-3

4,0x10-3

6,0x10-3

8,0x10-3

1,0x10-2

TN

T1

c

bV/V = (a+b+c)/3

a

SmH = 0

i = (l/

l)i

T (K)

Samarium

Thermal Expansion

9M.Rotter „Magnetostriction“ Course Lorena 2007

Samarium

Magnetostriction

10M.Rotter „Magnetostriction“ Course Lorena 2007

Tm

.... Strongly anisotropic Systems have to be measured with great care !!!

From Zochowski et al.[cap dilatometry J. Magn. Magn. Mat. 104-107, 1515 (1992). ].

?

TN=54K

11M.Rotter „Magnetostriction“ Course Lorena 2007

Forced magnetostriction of Tm a single crystal. Circles represent the data measured by Zochowski et al.[cap dilatometry J. Magn. Magn. Mat. 104-107, 1515 (1992). ]. Squares represent the data obtained by Barcza. [TU Vienna]. Crosses represent the neutron diffraction data obtained at IN12. Triangles the data obtained by A. Lindbaum glueing the sample [TU Vienna].

Tm