ggplot2 - geom_line generating line equal to a ladder - r

Question

I verified that when using geom_line the resulting graph is not formed by solid lines, the lines look like a ladder.
Would anyone know how to get solid lines?
Here is the code used.
data base
0;0
0.000700;1.050
0.001750;1.100
0.003800;1.150
0.029110;1.200
0.130900;1.240
0.341428;1.303
`library(tidyverse)
library(reprex)
SAT <- read.delim("Curva_Tipica.txt", header = FALSE, encoding = "UTF-8")
SAT <- str_split(SAT[[1]],";")
length_SAT <- length(SAT) + 1
curva_VxI <- tibble(
.rows = length_SAT,
I = 0,
V = 0,
)
for (linha in 2:length_SAT) {
curva_VxI$I[linha] <- as.double(SAT[[linha-1]][1])
curva_VxI$V[linha] <- as.double(SAT[[linha-1]][2])
}
Xac <- (curva_VxI$V[length_SAT] - curva_VxI$V[length_SAT-1])/(curva_VxI$I[length_SAT] - curva_VxI$I[length_SAT-1])
Vj <- curva_VxI$V[length_SAT] - Xac*curva_VxI$I[length_SAT]
Xac_grafico <- tibble(
x = c(0, 1),
y = c(0, Xac)
)
Vj_grafico <- tibble(
x = c(0),
y = c(Vj)
)
theme_set(theme_bw())
ggplot() +
geom_point(
data = curva_VxI,
aes(x = I, y = V),
color = "orange",
size = 2
) +
geom_line(
data = curva_VxI,
aes(x = I, y = V),
color = "orange",
linewidth = 1
) +
geom_point(
data = Xac_grafico,
aes(x = x, y = y),
color = "blue",
) +
geom_line(
data = Xac_grafico,
aes(x = x, y = y),
color = "blue",
linewidth = 1,
linetype = "solid",
) +
labs(
y = "V (pu)",
x = "I (pu)"
) +
coord_cartesian(
xlim = c(0, 1),
ylim = c(0, 1.5),
expand = FALSE,
clip = "off"
) +
scale_y_continuous(sec.axis = sec_axis(~.*1, "Xac (pu)")) +
theme(
axis.title.x = element_text(margin = margin(t = 10), size = 12, face = "bold"),
axis.title.y = element_text(margin = margin(r = 10), size = 12, face = "bold"),
axis.text.x = element_text(size = 10),
axis.text.y = element_text(size = 10),
legend.position = "top",
# plot.background = element_rect(fill = "gray60"),
plot.margin = margin(t = 1, r = 1, b = 0.5, l = 0.5, unit = "cm"),
)`
code output
expected result
result obtained