  THz generation from femtosecond photoexcited spintronic heterostructures has
recently become a versatile tool for investigating ultrafast spin-transport and
transient charge-current in a non-contact and non-invasive manner. The same
from the orbital effects is still in the primitive stage. Here, we
experimentally demonstrate orbital-to-charge current conversion in metallic
heterostructures, consisting of a ferromagnetic layer adjacent to either a
light or a heavy metal layer, through detection of the emitted THz pulses.
Temperature-dependent experiments help to disentangle the orbital and spin
components that are manifested in the respective Hall-conductivities,
contributing to THz emission. NiFe/Nb shows the strongest inverse orbital Hall
effect with an experimentally extracted value of effective Hall-conductivity,
\sigma_SOH^int^eff ~ 195 {\Omega}^(-1){cm}^(-1), while CoFeB/Pt shows maximum
contribution from the inverse spin Hall effect. In addition, we observe nearly
ten-fold enhancement in the THz emission due to pronounced orbital-transport in
W-insertion heavy metal layer in CoFeB/W/Ta heterostructure as compared to the
CoFeB/Ta bilayer counterpart.
