Isomeric and β-decay spectroscopy of 173,174Ho

β-decay spectroscopy of 173,174Ho (Z =67, N =106,107) was conducted at Radioactive Isotope Beam Factory at RIKEN by using in-flight fission of a 345-MeV/u 238U primary beam. A previously unreported isomeric state at 405 keV with half-life of 3.7(12) μs and a spin and parity of (3/2+) is identified in 173 Ho. Moreover, a new state with a spin and parity of 9− was discovered in 174 Er. The experimental log ft values of 5.84(20) and 5.25(18) suggest an allowed-hindered β decay from the ground state of 174Ho to the Kπ=8−isomeric state in 174Er. Configuration-constrained potential energy surface (PES) calculations were performed and the predictions are in reasonable agreement with the experimental results.Part of the WAS3ABi was supported by the Rare Isotopes Science Project which is funded by MSIP and NRF of Korea. This work was supported by JSPS KAKENHI Grants No. 24740188, No. 25247045, and No. 25287065, STFC (UK authors), the UK National Measurement Office (P.H.R.), the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC02-06CH11357 (F.G.K.), NRF Korea Grants No. 2016R1D1A1A09917463, No. 2017M2A2A6A02071071 (C.S.L.), No. 2019R1F1A1058370, and No. 2016R1A5A1013277 (K.Y.C.), and Science Foundation Ireland under Grant No. 12/IP/1288 (O.J.R.)