SDW Induced Charge Stripe Structure in FeTe Department of Applied Physics, Hokkaido University Y....
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SDW Induced Charge Stripe Structure in FeTe Department of Applied Physics, Hokkaido University Y. Kawashima , K.Ichimura, J. Ishioka, K. Yamaya, S. Tanda Department of Physics, Hokkaido University T. Kurosawa, M. Oda
SDW Induced Charge Stripe Structure in FeTe Department of Applied Physics, Hokkaido University Y. Kawashima, K.Ichimura, J. Ishioka, K. Yamaya, S. Tanda
SDW Induced Charge Stripe Structure in FeTe Department of
Applied Physics, Hokkaido University Y. Kawashima, K.Ichimura, J.
Ishioka, K. Yamaya, S. Tanda Department of Physics, Hokkaido
University T. Kurosawa, M. Oda
Slide 2
Stripe Structure Usually occur with anisotropic interaction
Long range attractive interaction Short range repulsive interaction
Ex)Dipole-Dipole interaction
Slide 3
W. F. Wang et. al. New J. Phys. 11 045003(2009) Iron-based
Superconductors LaFePO(1111) Fe-P La-O Coexistence of magnetism and
superconductivity New Type Strong correlated system
Slide 4
Magnets and Iron-based Superconductors Magnet Iron-based
Superconductor ex)Fe, Ni, Coex)LaFePO,BaFe 2 As 2 Main Character
Spin Main Character Charge Spin-Spin Interaction StrongWeak New
Phase? Spin and Charge Spin Density Wave(SDW) Investigate the new
electronic state Our Purpose spin
Slide 5
FeTe Investigate the new electronic state by using FeTe Method
Fe Te a b c a b SDW transition was suggested A. Subedi et. al, PRB,
78, 134514 (2008) Cleaved
Slide 6
D(r,eV):Density of State of sample Sample was cleaved in ultra
high vacuum Temperature 6.8K Pressure 10 -8 Pa Scanning Tunneling
Microscopy/Spectroscopy(STM/STS) LT-UHV-STM/STS Feedback Circuit
Controller DoS FF F +V bias V bias E e-e- V I tip sample tip
sample
Slide 7
Experiments Sample preparation Sample was prepared by chemical
vapor transport method using I 2 nominal ratio Fe:Te=1:0.9 Put In
evacuated quartz tube and keep 700 for one week. The sample was
evaluated by energy dispersive X-ray spectroscopy. Prepared sample
1mm Good single crystalline sample was obtained
Slide 8
Electrical property measurement 3 He cryostat system T = 0.5K
300K DC four probes method Resistivity measurement Magnetization
measurement SQUID Magnetometer T = 2 K 300 K
Slide 9
58K SQUID H = 0.5T AFM transition at 58K 58K DC four probes
Heating anomaly at 58K SDW transition Result of Resistivity and
magetization measurement
Slide 10
STM Experimental Result (T=7.8K) 3.8 Te atom V bias : 0.9V I
tunnel : 0.7nA Current image 1nm Discovery of charge stripe
structure 3.8 Cleaved c
Slide 11
A B A 012 3 [nm] B 012 3 A B We can see the iron layer under
the tellurium layer. Te Fe Analyzing Stripe Structure
Slide 12
C 0 1 2 [nm] C C Two types of iron atoms form charge stripe
structure Analyzing Stripe Structure2
Slide 13
STS Experimental Result (T=7.8K) SDW gap structure T SDW ~58K
SDW =9meV
Slide 14
The model of SDW induced charge stripe structure When SDW was
formed on iron layer. nesting vector[110] Ferromagnetic structure
Antiferromagnetic structure Antiferromagnetic and ferromagnetic
direction by SDW. Crystal Structure: 4-fold rotation Spin
Structure: 2-fold rotation
Slide 15
Other Electrons have strong coulomb interaction +Reducing
rotation symmetry caused by SDW SDW induced charge stripe structure
Reduce off-site coulomb interaction
Slide 16
SDW Charge Stripe The image of our model
Slide 17
Charge Order and Charge Stripe at Strong correlated system
Charge order in organic conductors H. Seo, JPSJ, 69,No. 3,805(2000)
Strong coulomb interaction relate to charge stripe structure. J. M.
Tranquada et. al, Nature,375, 561 (1995) Charge stripe in HTSC
Anisotropic structure & Charge localize Mott-insulator Base
Stripe
Slide 18
Strong Correlative Systems Organic Conductors Low transfer
energy Anisotropic crystal structure Cuprate Superconductors High
on-site coulomb energy Isotropic crystal structure Mott-insulator
base(half-filled) Iron-based Superconductors High off-site coulomb
energy Isotropic crystal structure (Semi)Metal base New E-Crystal
MX 1
Slide 19
How do we form the stripe structure by isotropic interaction
without structural anisotropy? Isotropic repulsive interaction
particle form stripe structure on simulation. G. Malescio and G.
Pellicane, Nature Materials, 2, 97 (2003) Can Charges form stripe
structure only themselves?
Slide 20
Summary Make single crystalline sample of FeTe Discover the
charge stripe structure on FeTe by STM Propose the model of SDW
induced charge stripe structure Results and Disscusion Thank you
very much for your attention. MX 1 series is new materials of two
dimensional crystal.