Quasi-two-dimensional Fermi surfaces with localized $f$ electrons in the layered heavy-fermion compound ${\mathrm{CePt}}_2{\mathrm{In}}_7$

We report measurements of the de Haas–van Alphen effect in the layered heavy-fermion compound ${\mathrm{CePt}}_2{\mathrm{In}}_7$ in high magnetic fields up to 35 T. Above an angle-dependent threshold field, we observed several de Haas–van Alphen frequencies originating from almost ideally two-dimensional Fermi surfaces. The frequencies are similar to those previously observed to develop only above a much higher field of 45 T, where a clear anomaly was detected and proposed to originate from a change in the electronic structure [M. M. Altarawneh et al., Phys. Rev. B 83, 081103 (2011)]. Our experimental results are compared with band structure calculations performed for both ${\mathrm{CePt}}_2{\mathrm{In}}_7$ and ${\mathrm{LaPt}}_2{\mathrm{In}}_7$, and the comparison suggests localized $f$ electrons in ${\mathrm{CePt}}_2{\mathrm{In}}_7$. This conclusion is further supported by comparing experimentally observed Fermi surfaces in ${\mathrm{CePt}}_2{\mathrm{In}}_7$ and ${\mathrm{PrPt}}_2{\mathrm{In}}_7$, which are found to be almost identical. The measured effective masses in ${\mathrm{CePt}}_2{\mathrm{In}}_7$ are only moderately enhanced above the bare electron mass $m_0$, from $2m_0$ to $6m_0$.

Figure 1

(a) The oscillatory torque signal after subtracting the nonoscillating background in ${\mathrm{CePt}}_2{\mathrm{In}}_7$ for magnetic field applied at $6^{\circ }$ off the $c$ axis at 50 mK. (b) A high-field zoom of the dHvA oscillations from (a) plotted as a function of the inverse magnetic field. (c) and (d) FFT spectra of the dHvA oscillations from (a) over equal $1/B$ intervals below (14–20 T) and above (20–35 T) 20 T, respectively.

Figure 2

dHvA oscillations in ${\mathrm{CePt}}_2{\mathrm{In}}_7$ for magnetic field applied at several small angles from the $c$ towards the $a$ axis at 50 mK. The arrows indicate approximately the field above which high dHvA frequencies start to develop for each orientation of the magnetic field.

Figure 3

Calculated band structure along the symmetry axes for ${\mathrm{LaPt}}_2{\mathrm{In}}_7$ (left) and ${\mathrm{CePt}}_2{\mathrm{In}}_7$ (right). The Fermi level is denoted by $E_F$.

Figure 4

Calculated density of states for ${\mathrm{LaPt}}_2{\mathrm{In}}_7$ (top) and ${\mathrm{CePt}}_2{\mathrm{In}}_7$ (bottom). $E_F$ denotes the Fermi level.

Figure 5

Calculated FSs of ${\mathrm{LaPt}}_2{\mathrm{In}}_7$ (left) and ${\mathrm{CePt}}_2{\mathrm{In}}_7$ (right). Solid and dotted lines indicate the two extreme cross sections of the main FS sheets of ${\mathrm{LaPt}}_2{\mathrm{In}}_7$. These orbits give rise to the experimentally observed dHvA frequencies when the magnetic field is applied along the $c$ axis.

Figure 6

The angle dependence of the experimentally observed dHvA frequencies in ${\mathrm{CePt}}_2{\mathrm{In}}_7$ (open circles) is shown together with the results of band structure calculations (solid circles) performed for (a) ${\mathrm{LaPt}}_2{\mathrm{In}}_7$ and (b) ${\mathrm{CePt}}_2{\mathrm{In}}_7$. The former corresponds to ${\mathrm{CePt}}_2{\mathrm{In}}_7$ with localized $f$ electrons.

Figure 7

High-field dHvA oscillations (a) and their Fourier spectrum (b) in ${\mathrm{PrPt}}_2{\mathrm{In}}_7$ for magnetic field applied at $6^{\circ }$ from the $c$ axis at 30 mK.

Figure 8

Comparison of the experimentally observed angle dependence of the dHvA oscillations in ${\mathrm{CePt}}_2{\mathrm{In}}_7$ (open circles) and ${\mathrm{PrPt}}_2{\mathrm{In}}_7$ (solid triangles) with the result of the calculations for ${\mathrm{LaPt}}_2{\mathrm{In}}_7$ (solid squares). Calculated dHvA frequencies lower than 500 T are not shown for clarity.

Figure 9

Amplitude of the dHvA oscillations in ${\mathrm{CePt}}_2{\mathrm{In}}_7$ as a function of temperature for $\alpha$, $\beta$, and $\gamma$ branches that originate from the main quasi-2D FSs. Insets show the data obtained on a smaller sample at different angles and over different temperature ranges. The lines are fits by the standard Lifshitz-Kosevich formula [37].

Figure 10

Angle dependence of the experimental dHvA frequencies plotted as $Fcos\left(\theta \right)$ for the three main FS sheets of ${\mathrm{CePt}}_2{\mathrm{In}}_7$. Solid lines represent the data average of $Fcos\left(\theta \right)$ for each FS.