We report a study of fermiology,electrical anisotropy,and Fermi liquid properties in the layered ternary boride MoAlB,which could be peeled into two-dimensional(2 D)metal borides(MBenes).By studying the quantum oscill...We report a study of fermiology,electrical anisotropy,and Fermi liquid properties in the layered ternary boride MoAlB,which could be peeled into two-dimensional(2 D)metal borides(MBenes).By studying the quantum oscillations in comprehensive methods of magnetization,magnetothermoelectric power,and torque with the firstprinciple calculations,we reveal three types of bands in this system,including two 2 D-like electronic bands and one complex three-dimensional-like hole band.Meanwhile,a large out-of-plane electrical anisotropy(ρbb/ρaa~1100 andρbb/ρcc~500,at 2 K)was observed,which is similar to those of the typical anisotropic semimetals but lower than those of some semiconductors(up to 10^(5)).After calculating the Kadowaki-Woods ratio(KWR=A/γ^(2)),we observed that the ratio of the in-plane Aa,c/γ^(2)is closer to the universal trend,whereas the out-of-plane Ab/γ^(2)severely deviates from the universality.This demonstrates a 2 D Fermi liquid behavior.In addition,MoAlB cannot be unified using the modified KWR formula like other layered systems(Sr_(2)RuO_(4)and MoOCl_(2)).This unique feature necessitates further exploration of the Fermi liquid property of this layered molybdenum compound.展开更多
The emerging Ni-based superconducting oxide thin films are rather intriguing to the entire condensed matter physics. Here, we report some brief experimental results on transport measurements for a 14-nm-thick supercon...The emerging Ni-based superconducting oxide thin films are rather intriguing to the entire condensed matter physics. Here, we report some brief experimental results on transport measurements for a 14-nm-thick superconducting Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) thin-film heterostructure with an onset transition temperature of~9.5 K. Photoluminescence measurements reveal that there is negligible oxygen vacancy creation in the SrTiO_(3) substrate during thin-film deposition and post chemical reduction for the Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) heterostructure. It was found that the critical current density of the Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) thin-film heterostructure is relatively small, ~4×10^(3) A·cm^(-2). Although the surface steps of SrTiO_(3) substrates lead to an anisotropy for in-plane resistivity, the superconducting transition temperatures are almost the same. The out-of-plane magnetotransport measurements yield an upper critical field of~11.4 T and an estimated in-plane Ginzburg–Landau coherence length of~5.4 nm. High-field magnetotransport measurements up to 50 T reveal anisotropic critical fields at 1.8 K for three different measurement geometries and a complicated Hall effect. An electric field applied via the SrTiO_(3) substrate slightly varies the superconducting transition temperature. These experimental results could be useful for this rapidly developing field.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12004123,51861135104,and 11574097)the National Key Research and Development Program of China(Grant No.2016YFA0401704)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.2019kfy XMBZ071)the China Postdoctoral Science Foundation(Grant No.2018M630846)。
文摘We report a study of fermiology,electrical anisotropy,and Fermi liquid properties in the layered ternary boride MoAlB,which could be peeled into two-dimensional(2 D)metal borides(MBenes).By studying the quantum oscillations in comprehensive methods of magnetization,magnetothermoelectric power,and torque with the firstprinciple calculations,we reveal three types of bands in this system,including two 2 D-like electronic bands and one complex three-dimensional-like hole band.Meanwhile,a large out-of-plane electrical anisotropy(ρbb/ρaa~1100 andρbb/ρcc~500,at 2 K)was observed,which is similar to those of the typical anisotropic semimetals but lower than those of some semiconductors(up to 10^(5)).After calculating the Kadowaki-Woods ratio(KWR=A/γ^(2)),we observed that the ratio of the in-plane Aa,c/γ^(2)is closer to the universal trend,whereas the out-of-plane Ab/γ^(2)severely deviates from the universality.This demonstrates a 2 D Fermi liquid behavior.In addition,MoAlB cannot be unified using the modified KWR formula like other layered systems(Sr_(2)RuO_(4)and MoOCl_(2)).This unique feature necessitates further exploration of the Fermi liquid property of this layered molybdenum compound.
基金financially supported by the National Natural Science Foundation of China(Nos.51822101,51861135104 and 51771009)。
文摘The emerging Ni-based superconducting oxide thin films are rather intriguing to the entire condensed matter physics. Here, we report some brief experimental results on transport measurements for a 14-nm-thick superconducting Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) thin-film heterostructure with an onset transition temperature of~9.5 K. Photoluminescence measurements reveal that there is negligible oxygen vacancy creation in the SrTiO_(3) substrate during thin-film deposition and post chemical reduction for the Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) heterostructure. It was found that the critical current density of the Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) thin-film heterostructure is relatively small, ~4×10^(3) A·cm^(-2). Although the surface steps of SrTiO_(3) substrates lead to an anisotropy for in-plane resistivity, the superconducting transition temperatures are almost the same. The out-of-plane magnetotransport measurements yield an upper critical field of~11.4 T and an estimated in-plane Ginzburg–Landau coherence length of~5.4 nm. High-field magnetotransport measurements up to 50 T reveal anisotropic critical fields at 1.8 K for three different measurement geometries and a complicated Hall effect. An electric field applied via the SrTiO_(3) substrate slightly varies the superconducting transition temperature. These experimental results could be useful for this rapidly developing field.
