Muon-spin-relaxation and inelastic neutron scattering investigations of the caged-type Kondo semimetals: CeT₂Al₁₀(T = Fe, Ru and Os)

Abstract

The effects of electron (Ir) and hole (Re) doping on the hybridization gap and antiferromagnetic order have been studied by magnetization, muon spin relaxation (µ + SR), and inelastic neutron scattering on the polycrystalline samples of Ce(Os1−xIrx)2Al10 (x = 0.08 and 0.15) and CeOs1.94Re0.06Al10. µ + SR spectra clearly reveals magnetic ordering below 20 and 10 K for x = 0.08 and 0.15 samples respectively with a very weak signature of oscillations of the muon initial asymmetry at very short time scale. Our important findings are that small amount of electron doping (i) completely suppress the inelastic magnetic excitations near 11 meV down to 2K, which were observed in the undoped compound, and the response transforms into a broad quasielastic response and (ii) the internal field at the corresponding muon site is remarkably enhanced by about ten times compared with the parent compound. On the other hand with small amount of hole (3% Re) doping the intensity of the inelastic magnetic excitations near 11 meV is reduced significantly. The main origin of the observed doping effect is an extra 5d electrons being carried by Ir and a hole carried by Re compared with that the Os atom. The obtained results demonstrate a great sensitivity of the carrier doping and provides additional ways to study their anomalous magnetic properties.

X-Ray Diffraction Study of CeT2Al10 (T = Ru, Os) at Low Temperatures and under Pressures

“…There is no distinct difference around T N out of this experimental error attributed to the change of pressure and to the shrink of GM refrigerator by cooling. These results do not contradict to the previous lattice parameters obtained from neutron diffraction with a small anomaly in the case of b parameter at 30 K, because the error bar of neutron diffraction is smaller [12].…”

Neutron diffraction study of magnetic order inNdFe2Al10

“…The overall picture is thus that of weakly interacting integral-valence rareearth ions. Interestingly, anomalies have been observed in specific heat, 7 µSR, 12 and electrical resistivity 13 measurement at temperatures close to 2-2.5 K, suggesting the possible existence of a second transition below T N . However, no indication of the nature of that transition has been reported so far.…”

Contrasting effect of La substitution on the magnetic moment direction in the Kondo semiconductorsCeT2Al10(T=Ru,Os)

“…In recent years, the magnetic and transport properties of Ce-based ternary compounds of type CeT 2 Al 10 (T = Fe, Ru and Os), which crystalline in the orthorhombic structure (space group No 63 Cmcm) [1], have generated strong interest in both theoretical and experimental condensed matter physics [2][3][4][5][6][7][8][9][10][11]. This interest arose due to the various ground states observed in this family of Cecompounds.…”

“…The results obtained for the two iso-electronic compounds are therefore an indication that the center of gravity of the 4f −band is lying on opposite sides of the E F : the 4f − spectral weight in CeRu 2 Al 10 is most likely close to but below the E F whereas in CeOs 2 Al 10 , the 4f band is most likely above the E F due to the more extended nature of the 5d band of Os compared to the 4d band of Ru. The 3d transition metal compound CeFe 2 Al 10 exhibits Kondo insulating behavior with a transport−derived gap of 15 K [3], while an NMR study reveals a much larger value of the gap, namely 110 K [18].…”