Suppressed Andreev Reflectionat the Normal-Metal / Heavy-FermionSuperconductor CeCoIn5 InterfaceWan Kyu Park et al.cond-mat/0507353 (2005)

CeCoIn5

CeCoIn5TC = 2.3K HoCoGa5 CeIn3 CoIn2 dx2-y2 dxy K.Izawa et al. PRL (2001)H.Aoki et al. Cond Mat (2004) d

Point Contact75 mmG.E.Blonder et al. PRB (1983)Nb wirea = contact radiusl = mean free path ( a / l 1 ) (ballistic) Andreev Au Tip etching

Andreev ReflectionE D N-S ( Hd(x) ) BTK modelA : C :

Andreev ReflectionZ = 0Z = 0.5Z = 1.5Z =5.0T = 0 INS = 2N(0)evFS[f0(E-eV) - f0(E)][1+A(E) - B(E)]dEZ = kFH / 2EF Z

EXPERIMENTS001,110,100300 mK 12 T (001),(110) , 0 T

Ballistic or diffusive?ballistic!ballistic limit (K 1) , R0 = 4rl / 3pa2diffusive limit (K 0) , R0 = r / 2aRN = R0(1 + Zeff) 1.1 W , Zeff 0.3652a 460 K l / a 1 a R0 4rl / 3pa2 + r / 2a G.Wexler Proc. Phys. Soc (1966)l 810 Movshovich et al. PRL (2001)l k / T2 N.E.Hussey Adv. Phys. (2002) l 5 mm (400 mK) l 6500 R.J.Ormeno et al. PRL (2002)

RESULTS 1conductance of (001) Point-Contact Junction60 K 400 mK- mV 45 K 2.6 KTCH.Shishido JPSJ (2002)

conductance of (001) Point-Contact Junction3% 13.3% HFS UPt3H.v.Lohneysen Physica B (1996)RESULTS 1

s wave?fitting conductance spectra using s-wave BTK modelZeff = 0.346D(0) = 404 meV 2 D(0) /kBTC = 4.08 T = TC t G = h / 2pts

EXTENDED VERSION OF THE BTK MODEL (EBTK model)BTK model d D(T,f) = D(T) cos 2fa : a = 0 or (001)a = p / 4

d wave?Zeff = 0.365D(0) = 460 meV 2 D(0) /kBTC = 4.64 G = h / 2pt = 218 meVbest fit curve at 400 mK using d-wave BTK model s

RESULTS 2conductance of (110) Point-Contact Junction (13.3 % vs 11.8 %) ( 1 meV) (001)

dx2-y2 ? dxy ? (110) dx2-y2(001) and (110) at 400 mK and 410 mK(110)

CONCLUSIONSAu/CeCoIn5 N/HFS

d

CeCoIn5 dx2-y2

Andreev (110)