Chern insulators, which are the lattice analogs of the quantum Hall states, can potentially manifest high-temperature topological orders at zero magnetic field to enable next-generation topological quantum devices 1-3. To date, integer Chern insulators have been experimentally demonstrated in several systems at zero magnetic field 3, 4-8, but fractional Chern insulators have been reported only in graphene-based systems under a finite magnetic field 9,10. The emergence of semiconductor moiré materials 11, which support tunable topological flat bands 12,13, opens a new opportunity to realize fractional Chern insulators 13-16. Here, we report thermodynamic evidence of both integer and fractional Chern insulators at zero magnetic field in small-angle twisted bilayer MoTe2 by combining the local electronic compressibility and magneto-optical measurements. At hole filling factor [Formula: see text] = 1 and 2/3, the system is incompressible and spontaneously breaks time reversal symmetry. We show that they are integer and fractional Chern insulators, respectively, from the dispersion of the state in filling factor with applied magnetic field. We further demonstrate electric-field-tuned topological phase transitions involving the Chern insulators. Our findings pave the way for demonstration of quantized fractional Hall conductance and anyonic excitation and braiding 17 in semiconductor moiré materials.

Although high-transition-temperature (high-Tc) superconductivity in cuprates has been known for more than three decades, the underlying mechanism remains unknown1-4. Cuprates are the only unconventional superconductors that exhibit bulk superconductivity with Tc above the liquid-nitrogen boiling temperature of 77 K. Here we observe that high-pressure resistance and mutual inductive magnetic susceptibility measurements showed signatures of superconductivity in single crystals of La3Ni2O7 with maximum Tc of 80 K at pressures between 14.0 GPa and 43.5 GPa. The superconducting phase under high pressure has an orthorhombic structure of Fmmm space group with the [Formula: see text] and [Formula: see text] orbitals of Ni cations strongly mixing with oxygen 2p orbitals. Our density functional theory calculations indicate that the superconductivity emerges coincidently with the metallization of the σ-bonding bands under the Fermi level, consisting of the [Formula: see text] orbitals with the apical oxygen ions connecting the Ni-O bilayers. Thus, our discoveries provide not only important clues for the high-Tc superconductivity in this Ruddlesden-Popper double-layered perovskite nickelates but also a previously unknown family of compounds to investigate the high-Tc superconductivity mechanism.