An insulating salt as a laboratory for

1
An insulating salt as a laboratory for emergent
quantum phenomena

• G. Aeppli (LCN)
• J. Brooke (NEC/UChicago)
• T. F. Rosenbaum (UChicago)
• D. Bitko (UChicago)
• H. Ronnow (PSI/NEC)
• D. McMorrow (LCN)
• R. Parthasarathy (UChicago/Berkeley)
• S. Ghosh (UCSB)
• S. Coppersmith (Wisconsin)

2
Simplest quantum magnet
Ising model in a transverse field
Quantum fluctuations matter for G ? 0
PM
1
GckTcJ
0.5
FM
1
0
0.5
3
Realizing the transverse field Ising model, where
can vary G LiHoF4

• g14 doublet
• 9K gap to next state
• dipolar coupled

4
Realizing the transverse field Ising model, where
can vary G LiHoF4

• g14 doublet
• 9K gap to next state
• dipolar coupled

5
(No Transcript)
6
(No Transcript)
7
Susceptibility

• Real component diverges at FM ordering
• Imaginary component shows dissipation

8
c vs T for Ht0

• D. Bitko, T. F. Rosenbaum, G. Aeppli, Phys. Rev.
  Lett.77(5), pp. 940-943, (1996)

9
Now impose transverse field
10
(No Transcript)
11
(No Transcript)
12
165Ho3 J8 and I7/2 A3.36meV
13
WAltJgtI 140meV
14
Diverging c
15
Magnetic Mass

a

• The Ising term ? energy gap 2J
• The G term does not commute with
• Need traveling wave solution
• Total energy of flip

16
Magnetic Mass

a

• The Ising term ? energy gap 2J
• The G term does not commute with
• Need traveling wave solution
• Total energy of flip

17
Magnetic Mass

a

• The Ising term ? energy gap 2J
• The G term does not commute with
• Need traveling wave solution
• Total energy of flip

18
Magnetic Mass

a

• The Ising term ? energy gap 2J
• The G term does not commute with
• Need traveling wave solution
• Total energy of flip

19
Magnetic Mass

a

• The Ising term ? energy gap 2J
• The G term does not commute with
• Need traveling wave solution
• Total energy of flip

20
Spin Wave excitations inthe FM LiHoF4
Energy Transfer (meV)
1
1.5
2
21
Spin Wave excitations inthe FM LiHoF4
Energy Transfer (meV)
1
1.5
2
22
What happens near QPT?
23

• H. Ronnow et al. Science (2005)

24
(No Transcript)
25
WAltJgtI 140meV
26
(No Transcript)
27

• d2s/dWdwSfltfS(Q)0gt2d(w-E0Ef) where
• S(Q) SmSmexpiq.rm

28
summary

• Electronic coherence limited by nuclear spins
• QCP dynamics radically altered by simple
  spectator degree of freedom
• Nuclear spin bath pulls back quantum system
  into classical regime

29
wider significance

• Connection to single molecule dynamics

best Electronic- TFI
30
conclusion

• slaved degrees of freedom which are classically
  irrelevant can have qualitative quantum impact